Acceleration issue

[JDM VANMAN]

So the other day I was driving to work and was getting on the express lanes, as I shifted thru the gears and was driving in 4th gear at 40mph I noticed the van wasn't speeding up?? I thought I was in the wrong gear but when I checked I was indeed in 4th gear, I proceeded to shift into 5th only for the van continue to lose speed so I pulled over onto the shoulder.

As I took it out of gear and coasted over to the shoulder safely I noticed that the idle was at a steady 750-800rpm, no trembling, shimmying or hesitation, the needle was solid. I checked the vitals, temperature and oil seemed normal. I sat there for a few minutes to see if the idle would change but it was good. While in neutral I started to push down on the accelerator about half way but the engine would only rev up to 1900-2100 rpms and no more. It was just bouncing in that range vroom...vroom... vroom... And then I let off and it would go back to normal idle.

I sat for 10 minutes repeating this and then it did start to go up to 4300 rpms but it struggled to get there, it only did this a couple of time before going back to the original problem. So I called AAA and they towed me to the shop. They finally came 3 hours later after I called them and chewed them out for leaving me stranded on the express lanes and the State Trooper told me kindly to move my dusty bucket off the freeway before they switched directions.

I did take a video so I could show it to the guys at the shop cause I know from the past experience the van will act up with me but when I take it to the shop then all is fine and dandy!! They looked at the video and said as long as it's still acting up they'll be able to diagnose the issue. And of course they've had it for a week and it's running just fine.

They've left the Van running for hours and took it on test drives between working on other cars and still nothing?? But there are 3 possible things they said could be the problem-
1) air flow meter
2) fuel filter
3) fuel pump

I asked them if it could be a vacuum leak, broken air intake tube, or bad TPS and they said more then likely not, but if it'll act up then they'll know for sure.

Has anyone else experienced the same problem and what was the final resolution? Thank you for your time, knowledge and inputs in advance:thmbup:

[Megadysart]

They've left the Van running for hours and took it on test drives between working on other cars and still nothing?? But there are 3 possible things they said could be the problem-
1) air flow meter
2) fuel filter
3) fuel pump

If you haven't already, I would IMMEDIATELY replace the Fuel Pulsation Damper, or at the very least verify that it isn't leaking. Flounder has a write up on it -http://www.toyotavantech.com/forum/showthread.php?231-Replacing-your-fuel-pulsation-damper

I went on a road trip on my van awhile back, and a couple miles from the house my van started to sputter around 2k-2.5k RPM's. It went away after warming up completely so I thought little of it, and babied it the rest of the way. Spent 2 days in Payson and on the way back the stumbling and jerking at freeway speeds was frightening. I pulled over at an Orielly's still 15 miles from home and immediately smelled GAS. I placed my hand under the FPD and it was SPEWING gas out of the weep hole at the bottom. It's a miracle that I'm not dead/my van isn't burned to the ground. :wall: I spent a good 5-6 hours in that parking lot trying to figure out a way home. I ended up screwing a machine screw with a hex head and a copper washer into the hole, and jb qwik welded it to make sure nothing leaked. It held up well enough to get me home. (I WOULD NOT ADVISE THIS REPAIR; BUY THE PART OEM/EQUIVALENT OR BE SORRY).

I ordered an Airtex/Wells unit and it has held up fine.

Also check your injector connectors. During my initial head gasket replacement/necromancing of my van, I was impatient and broke the brittle 30 year old injector connectors. They don't lock down any more, but they function well enough. Occasionally (once a month or so) my van will have NO power and sound like a lawn mower, often out of nowhere. I have to pop the seat up and push the #1/#2 injector connector back into place and it solves the problem.

Good luck!

[JDM VANMAN]

Megadysart,

thanks for the reply, but it didn't turn out to be what suggested. The Van seems to be running fine with no issues found at this time or I should say unable to duplicate the problem. I think I'll be picking up sometime this week not unless it miraculously acts up again.

[timsrv]

I had this problem once but before I could diagnose it stopped on it's own. It only happened once and it was years ago. I suspected the air flow meter was hanging up, but who really knows. I seriously doubt it could be a fuel filter or a fuel pump. I would suspect a fuel filter if the problem persisted, but filters don't "magically" unplug themselves. If it were a fuel pump it would likely stop altogether and the van would stall. There's also a small chance it could be a glitch with the ECU or something else electronic like the coil or igniter.........but all these things are "shots it the dark" and can never be proven (unless the problem can be duplicated for testing). Hopefully it was just a fluke and it will not return. If it does return, hopefully it will remain until the issue can be properly diagnosed. Tim

[JDM VANMAN]

Thanks Tim,

yeah I'm hoping it's not serious, when stalled on the freeway I couldn't get it to go above the 1900-2100 rpm range and when it did, it was struggling. The shop said they fired it right up and started driving it around and it drove pretty nice for an "old girl"

They've been busy this week and I haven't gone in to check with them but I'll stop in today to get an update and take it home.

[djshimon]

Not sure should put this in a different thread but I had a similar problem recently with hesitation and my neighbor who's a long time mechanic asked if I used cheap gas recently and I started thinking(uh oh!) Yes I had and my other car(Volvo 240) has been running pretty crappy too. I went to a more standard gas station than the Space Age and put in the Plus and a bottle of that fuel cleaner(name?) and haven't had hesitation since! Woohoo gotta love easy solutions!
Moral of my story-I won't be buying cheap gas again.

[JDM VANMAN]

For me it hasn't been a fuel, fuel filter, AFM issues, it has happened again but these few times it was when it was raining and with out fail if I happened to drive thru a puddle of water and the water sprayed up under the van, and then I will loose acceleration almost instantaneously and have to pull over sputtering and putting to the side.

Once stopped in a safe location the idle will be rock solid at 750-800 rpm's but when I put it in gear it'll just sputter and put put with no acceleration, and when I leave it in neutral and push the accelerator The RPM gauge will never pass 1900-2200 rpms and will just jump up and down in that range. I'll sit in the van for about 10-15 minutes just holding the accelerator steady until it finally decides to start working like normal again. And then I drive away like nothing happened??

I'm thinking the water that sprays under the van goes somewhere causing this problem but not sure where?:?:

[djshimon]

I'd say check the distributor gasket or New cap. And plug wires-maybe water gets in there- But I'm just guessing.

[llamavan]

:whs:

Gwen

[JDM VANMAN]

Nice thanks for the heads up:thmbup:

[89TownAce]

VERY likely the distributor cap. It's a common problem on old Mini Coopers because the disty is right behind the grill. A lot of guys wrap their disty in a plastic bag when it rains.

[AD2101]

Could be the gasket (or lack thereof) between the distributor and distributor cap. Mine does the same thing the 3 times a year it rains heavy out here.

http://www.toyotavantech.com/forum/showthread.php?2552-Snorkel

[JDM VANMAN]

Could be the gasket (or lack thereof) between the distributor and distributor cap. Mine does the same thing the 3 times a year it rains heavy out here.

http://www.toyotavantech.com/forum/showthread.php?2552-Snorkel

Nice thank you for the redirect for the gasket part numbers and the confirmation of having a similar issue as mine!!:thmbup:

I ordered both gaskets that were listed by Tim in the 2nd posting of that thread.

Thank you

JDM

[djshimon]

JDM I'm still having the same issue as you were and it's when I hit a puddle-van runs like crap for 2-3 minutes. I'm wondering if it's the fusible link that's behind the driver's wheel? When I checked it today it was wet at the bolt connections so I put some dielectric grease on it and wrapped it in a plastic bag and taped it-if this seems to help I may end up moving the link or sealing it better. I don't get the engine flash(throwing a code) when this issue appears which is might help to narrow things downs, somehow. Pretty frustrating this problem but at least it's mostly narrowed down to wet days.
Also, I have the new gasket and cap on my distributor but maybe I'll wrap it in a plastic bag if this continues just to try it.

[djshimon]

I have finally diagnosed my acceleration/hesitation issue and it is definitely wet distributor related. I sprayed some water on the distributor and it hesitated and was very unhappy-keep in mind I changed both gaskets on the distributor, cap and rotor <6 months ago and it ran much better but would still choke and hesitate after driving through puddles or on heavy rains.
I thought about sealing up the distributor cap and the weep hole on the bottom with silicone but then read that ozone builds up inside if sealed=bad. Instead I put a bunch of dielectric grease around the seal which helped even more but did not totally get rid of the problem completely.
Next will try a new o-ring for the distributor shaft and will update if that works.
Maybe the plastic bag trick too.
Otherwise I might have to try a 12volt air pump into a hole on the dizzy which will then make it able to ford streams!
Otherwise I don't know any other options.

[timsrv]

Did you ever change the distributor cap and wires? Sometimes contaminants can get on the cap/wires and cause on-going issues. I had once gotten antifreeze on/in my cap & wires when a hose blew. After that the van would give me trouble in high humidity conditions. It's because the antifreeze residue would attract moisture and recreate problems every time humidity was high. Problem completely disappeared when I changed the cap and wires. Tim

[djshimon]

I did the cap, rotor and both dizzy gaskets a few months ago and the problem was less but still happens on puddles and heavy rain. The wires are 2 years old and I put dielectric grease where they connect to the cap and the spark plugs. Hoping the distributor shaft gasket helps.

[PNW vanwagon]

had this exact problem with the van i purchased approx 6 months ago: started and ran rough when it was wet. got worse and worse. would run fine after running a hairdryer on the cap for 5 minutes so i knew it was allowing moisture inside. i did new distributor cap, rotor, dist gasket, spark plugs and plug wires. everything runs great now even in pouring rain.

i got the OEM dist gasket and it didn't exactly match the new dist cap i purchased from auto parts store. just to be safe i added a very tiny bead of blue RTV around the edge of the cap to be sure it was sealed well

definitely cover your fusible link! it gets very wet when the roads are rainy. i used a foil to-go container from the dollar store to make a sheath. works real well for a temporary fix.

[djshimon]

Thanks Tim and PNWvan. I'll continue to work on this one. Now that it's just about summer here I have some time to play with.
I also wanted to put it out there in case other people are having this problem. It didn't show any codes so was a pain to figure out.

[JDM VANMAN]

Update, I’ve replaced the distributor gaskets but still having the acceleration in the rain, still can’t nail it down. I’m hoping that I’m using the correct terminology in this thread so I’m posting a video-

https://youtu.be/V-MdzSdvS8Q

thank you:thmbup:

JDM

[djshimon]

JDM,
I guess I followed it up in this thread : https://www.toyotavantech.com/forum/showthread.php?6003-Rough-idle-stalling-when-raining-or-very-humid-hole-in-distributor&p=37112&highlight=rough#post37112
Have you tried spraying water on the distributor-just to rule out somewhere else it could be shorting? If it happens when you spray it and you have another distributor I'd swap 'em. Also how old is your dizzy cap?
From the other thread- I'm thinking after cap, wires and plugs I'd check your coil. I think Papay was right on in that thread-he spray coated his coil in rubber. Not sure how to test the coil for wet shorting besides checking resistance before and after spraying it with a mist.
Also make sure your drain holes in the distributor are clear.`

[JPERL]

I remember MAHLEEk had this exact issue symptoms and all and replacing the coil resolved the issue. Additionally maybe the exhaust is plugged or restricted?

[JDM VANMAN]

Also how old is your dizzy cap?

Thank you for the quick response!! The OEM cap is 4 years old and about 30k miles but as for the ignition coil don’t think it was replaced when I originally had a ton of work done when I first got the van??

I’m thinking that has to be the issue!!?? I checked on RockAuto and there’s about 4 different kinds, is there a “part of choice” you would go with or should I order an OEM part?

JPERL,

Thank you for the response I think I’ll be starting with replacing the coil and keep my fingers crossed!

Thank you:thmbup:

JDM

[djshimon]

Oem always seems better for Toyota but if it's an exhorbitant cost I'd get an aftermarket coil-others might weigh in here. If you're gonna be taking it out to replace it I'd check resistance on it before and after spraying it with water to see if it has an effect.

[timsrv]

Update, I’ve replaced the distributor gaskets but still having the acceleration in the rain, still can’t nail it down. I’m hoping that I’m using the correct terminology in this thread so I’m posting a video-

https://youtu.be/V-MdzSdvS8Q

thank you:thmbup:

JDM

JDM, that looks suspiciously like a "Fuel Cut RPM" system issue. It's not talked about much in the manual, but mentioned briefly on FI-74 (87 service manual). It's an emission feature that turns off the injectors while decelerating. It's controlled by the ECU (Electronic Control Unit) based on the info it's getting from the TPS (Throttle Position Sensor). If/when it does it again, disconnect the TPS to see if the issue goes away. If you can make it come and go by disconnecting/reconnecting the TPS, then it's a bad TPS. If disconnecting the TPS does not affect it, then it's either a short in the harness (between wires IDL & E1 somewhere between the TPS and the ECU) or it's a bad ECU. Good luck and please update with your findings. Tim

PS: Since it's affected by water, you should also check the seal on your TPS connector. If it's damaged there are aftermarket connectors available. Tim

[Flecker]

Thank you for the quick response!! The OEM cap is 4 years old and about 30k miles but as for the ignition coil don’t think it was replaced when I originally had a ton of work done when I first got the van??

I’m thinking that has to be the issue!!?? I checked on RockAuto and there’s about 4 different kinds, is there a “part of choice” you would go with or should I order an OEM part?

JPERL,

Thank you for the response I think I’ll be starting with replacing the coil and keep my fingers crossed!

Thank you:thmbup:

JDM


I nabbed this coil off of Amazon.
https://www.amazon.com/gp/product/B006PE1PB8/ref=ppx_yo_dt_b_asin_title_o09__o00_s00?ie=UTF8&psc=1

Seems to be working great so far! The old OEM one had burn marks on the top and the cover was cracked.

I'm not sure if there is a "choice" one, but taking out the old one sure made a difference with the idle. I still had the little rubber gasket under the original dizzy cap though.

[JDM VANMAN]

Tim,


thank you for the detailed reply as always, Lots of good info!!! But this happens when it’s raining and when I start to accelerate from 1st to 2nd gears, hit a puddle on the right side, and then instantaneous loss of acceleration. I’ll pull over and the idle will be steady except for when I push the accelerator down half way and then it’ll not pass the 2200rpm range.

On any other dry day the van will fire right up and run smooth all day long:thmbup: Although the TPS has never been replaced along with the ignition coil, that’ll be the starting point to help resolve this issue.

Flecker,

thank you for the link on the Delphi coil, I think that’s the one the shop put into my TownAce when I was having issues with that van and it’s been running fine. I wanted to OEM part in the TownAce but they had already diagnosed the issues and repaired it before I could ask for the OEM part.

Thank you I’ll keep you posted!!

JDM

[djshimon]

That is a little different than the symptoms i had. From what i remember: When I would hit a puddle the idle would go down to like 500rpm and when i would accelerate it would hesitate/stumble/run like crap at lower rpms until i got it up to about 2500-3000 then it would run ok. It didn't hit a limit like yours that i can remember. Very curious to hear the cause of this but i don't doubt Tim is right.

[JDM VANMAN]

Yes I don’t doubt Tim either ( I’m no where in the position to do that) but it only happens on acceleration and not deceleration, it’ll last for 6,8,10 minutes I’m guessing where the rpm’s just won’t go over the 2200 mark.

Did you happen to notice any peculiar smells when this happened to you? I would have to say I do smell something but can’t put my nose to what it is, it’s not something easy like burning clutch, radiator fluid.... I’m thinking it’s more of a rich exhaust smell when this happens. Eventually after holding the accelerator for the duration of time and it clears up the rpm’s start climbing back up like normal again and away I go???

Friday I went in to my Tech that works on the van and reviewed the whole scenario with him again and he said they did fill up a bottle and spray it on the distributor cap and in the general area and the van kept idling like normal, they did this when I asked them to replace the gaskets a while ago. I told him it only does it upon acceleration so one person would need to hold the accelerator to 2500 rpm’s while the other sprayed water. He just said “ahhh ok we’ll check it out”


It sucks cause it happens in the rain when I’m going to and from work 6am-9pm and it pitch dark, or I’m on the freeway. Oh and the most important... my lack of wrenching skills.
JDM

[djshimon]

Any chance a code showed up? I watched your video again and it's definitely different-mine was like a misfire-not saying it isn't your coil though (can't see from here!). I would probably have someone on the gas and I'd have a sprayer and I'd just go around spraying things one at a time until the problem rears its ugly head again.

[JDM VANMAN]

No man, every time it’s happened it’s been dark and plus I haven’t taken the time to learn how to pull codes even though there’s a very detailed thread on how to do it. :no:

The very first time it happened I had the van towed off the Express Lanes to the shop and by the time they started to work on it, it fired right up. Only thing I can do is drop it at the shop and pay them to recreate what I’ve been experiencing and get the explanation.

I’ve asked them to use the service connector to pull codes or I could even bring in the FSM but they just looked at me and laughed, not in a melicious way of course, they said they don’t use the Stone Tablets anymore. :LOL2:

JDM

[djshimon]

Stone tablet-it's a paperclip! But yeah it's a very simple machine compared to my 2013 Prius-quit laughing! Just thinking if a TPS code was thrown that'd give more Credence to Tim's theory. You should really check your codes it's fun-it's literally putting a paperclip into a yellow dangling connector and turning the van to "on" and counting the blinks. If you miss the blinks, they repeat. Well that's enough pushiness for tonight, until next time!:bluevan:

[VanCo]

I watched the video. That's 100% what fuel cut does on acceleration. Basically the computer is getting a signal the throttle is fully closed. It then limits injector output. If this happens when you're accelerating it will act as a kind of rev limiter at 2200 rpm. More than likely a tps wire, tps connector, or bad tps is getting wet and completing the circuit.

[Flecker]

I watched the video. That's 100% what fuel cut does on acceleration. Basically the computer is getting a signal the throttle is fully closed. It then limits injector output. If this happens when you're accelerating it will act as a kind of rev limiter at 2200 rpm. More than likely a tps wire, tps connector, or bad tps is getting wet and completing the circuit.


I think you nailed it man... When I first started tearing into my van a little over a month ago I ripped off all the access panels and pressure washed all the crapola out of the engine bay. Shortly there after mine started doing the same thing! Idle seems ok, but when I revved it I found it started cutting out in the upper rpm's. I pulled the codes and got a code 2 AND 11. I knew the afm circuit was having issues, the wiring was cut. Fixed that and still got a code 11 after the fact.

Ordered the new beck-arnley tps and everything went back to normal.

I think he needs a new tps. I ripped my throttle body off and cleaned and cleared all the vac ports as well... about a 2 hour job. I will say again, I am a huge fan of putting di-electric grease in ALL my plug fittings, it rules out the potential for faulty wiring connections (at least at the plugs)!

Pull the codes and if you see a code 7 OR 11, just get a new TPS. Amazon- https://www.amazon.com/gp/product/B000CB1VR8/ref=oh_aui_search_asin_title?ie=UTF8&psc=1

42 bux shipped if you have Prime~!
:dance2:

[timsrv]

..............but it only happens on acceleration and not deceleration, it’ll last for 6,8,10 minutes I’m guessing where the rpm’s just won’t go over the 2200 mark.

Yes, it's only supposed to happen on deceleration. Since it's happening on acceleration it would be a malfunction or an "issue" with that system (sorry I didn't make that more clear in my post).


It sucks cause it happens in the rain.............
JDM

And this is why I think you should check the TPS connector seal as well as the TPS and the harness. It could also be an issue with the ECU, but since that's much more sheltered from water splashes that's less likely. I suppose it's possible it could have a problem with humidity inside the ECU box (when conditions are right), but that's somewhat of a stretch. Tim

[JDM VANMAN]

Tim


No worries, I cling on to everything you say... Tim’s word is The Law when it come to diagnostic explanations but you know you have to talk to me like a 2nd grader because of my lack of wrenching skills!! :cnfsd::cnfsd::cnfsd:


I’m attaching a new video of the codes that came up when I jumped the ODB1 wire.
I got code 4 and 11 and code 7 and 12


I don’t think any codes have ever been cleared but after addressing them I’ll need to clear them out.


djshimon,


Thank you for building up my confidence in how easy it is to read the codes!!! Now teach me how to clear them!! :dance2:


Vanco,


Thank you for chiming your input and explanation this helps not just for me but everyone reading!!


Flecker,


Thank you for your link to a new TPS, I think I’ll order a new connector as well but I can’t seem to figure out which one is the correct one for the TPS?


I’m gonna order the new Ignition Coil, TPS and the TPS connector, thank you all for the inputs and redirects to parts!! Tremendously helpful!!


https://youtu.be/IYLidTY91JY

JDM

[Flecker]

4- water temp sensor
5- O2 sensor
7- TPS
11- switch signal


Theres a pdf on here that explains all this... http://www.toyotavantech.com/forum/content.php?195-Diagnostic-Codes-for-Toyota-Vanwagons-all-years

If those codes are all relevant your prolly at about 100 bux or so for the tps , O2 sensor (if bad, not unplugged) and the temp sensor (if it's bad and not just unplugged).


Again- for the parts...

O2 sensor : https://www.amazon.com/Denso-234-1056-Oxygen-Sensor/dp/B000C5SFSC/ref=sr_1_1?s=automotive&ie=UTF8&qid=1548641183&vehicle=1987-76-942-995--49-8-8-4776-1893-9-1-1996-191-4-0&sr=1-1&ymm=1987%3Atoyota%3Avan&keywords=o2+sensor

Temp sensor: https://www.amazon.com/Beck-Arnley-158-0134-Temperature-Sensor/dp/B000CB0192/ref=sr_1_3?s=automotive&ie=UTF8&qid=1548641236&vehicle=1987-76-942-995--49-8-8-4776-1893-9-1-1996-191-4-0&sr=1-3&ymm=1987%3Atoyota%3Avan&keywords=temperature+sensor


The tps is the one jacking with you more than anything though.

[timsrv]

I've used the Standard #S745 Connector (https://www.amazon.com/Standard-Motor-Products-S745-Pigtail/dp/B000IYLK02/ref=sr_1_1?ie=UTF8&qid=1548641376&sr=8-1&keywords=standard+motor+products+s745) for the TPS. FWIW, this should be considered a crucial connection and be soldered/shrink tubed to the harness. Wire nuts and/or solderless connectors may work as a temporary fix, but things like this should be sealed and protected as it reduces the risk of future issues.

As mentioned multiple times in other threads, once documented, it's recommended you clear codes then see what comes back. I'm guessing you'll see codes 7 & 11 come back (7 would explain the current problem you're having & 11 is also usually caused by a failing TPS). I sort of doubt 4 will come back as the van would run terrible all the time if that temp sensor was bad. Code 5 may or may not come back. The van can run decent with a bad o2 sensor but your performance and economy will suffer. Just follow the link Flecker gave and that should explain things in more detail. Here's a link that shows how to service and adjust your throttle body and TPS: https://www.toyotavantech.com/forum/showthread.php?1242-Article-Cleaning-the-Throttle-Body. Tim

[djshimon]

Even easier to clear codes, disconnect the battery cable from the negative (ground or -) battery terminal for about 30 seconds-60 if you're wanting to be thorough. Don't mess with the positive terminal. Some of your stored codes could be old but the tps one is probably the ongoing.

[JDM VANMAN]

Tanks guys, I’ve got all the parts ordered and they’ll be showing up in the next couple days!!:thmbup:

JDM