PDA

View Full Version : 5th gen 91GT surging issue, only @ partial throttle....Troubleshooters step inside!



chinaonnitrous1
02-04-2005, 07:47 AM
Alright, So i purchased this car a few weeks ago, with the intent to fix it. It is a 1991 Celica Gt 5spd, with 137k miles. Its in awesome condition. Except theres one problem.

The power surges at partial throtle, throughout the RPM range. Happens at about 1/3 throttle at any gear. It jerks heavily most of the time. At idle it bounces up or down 100-150 rpm. It bascially feels like the car is lugging around. No backfires. The car runs mainly rich upon warm up, its a noticable smell. Sometimes the car drives perfectly fine at any throttle position. Othertimes the gas needs to be atleast 2/3 down to run smoothly.

The previous owner had replaced/serviced:
New TPS sensor
Ignnition coil, wiring, plugs, plugs wires, cap, rotor.
O2 sensors (both of them Cali ediiton)
TPS sensor
Multiple Carbon deposit cleanings
Fuel system Cleaner
used propane to test for leaks (none)
Chevron Supreme/Plus fuel

Not sure what else to check out, BUT tonite, the motor was a little cold idling roughly, so i revved the motor up to redline and let off the gas. At about 3k rpm upon the Rev's dropping, the RPM's jumped up to about 4100 and the check engine light came on, as the Rpm's once again continued to fall. Once again i Revved the engine up, and let it wind down (foot off the gas) the check engine light came on once again at about 3k rpm as the needle jumped back up to 4k. I got the vehcile to repeat about 3-4 times. Each time the engine light shut off. From previous posts people say the code is stored. Hopefully i can get it pulled. Any other places other than toyota? I have an OBDII scanner...but obviously this car is before OBDII.


The only ohter time the Check engine light came on, was while I was trying to beat a yellow light. Ran the car to redline, then the light came on during acceleration.



Any ideas, thoughts, comments? I hope to share the progress of this vehicle with everyone, as it's had several people boggled as well as a few Toyota Techs. its spent hours being troubleshot at no avail....


Post away!

Larry =)
:popcorn:

chinaonnitrous1
02-04-2005, 07:47 AM
Oh ECU was also swapped out but to no avail.

Punisher
02-04-2005, 05:42 PM
Who installed the TPS? You might wanna play with that.. or have a Toyota service tech. set it to factory specs..

When I was goofing with my TPS on my 7AFE powered corolla a while ago, the CEL would come on at certain throttle points.. if I had the TPS adjusted wrong. So that could be your issue.

Also check that the timing is correct.. and don't forget to short the two pins in the diag box first.. believe it's TE1 and E1... so that way you get a proper timing reading..

Let me tell ya what happened with my 90 GTS... It had some similar issues.. like power surging or flat spots.. Most of the time it would get this flat spot somewhere around 3-4K.. then it just felt like all the rev's after that weren't doing shit.. bad gas mileage.. excessive jerking or bucking... Well, once I put in GOOD ignition parts.. NGK plugs.. NGK wireset (only cost 27.00 cheaper than the autostore shit brand I had before).. new cap and new rotor.. things got slightly better... Mind the 5SFE is really sensitive to ignition issues.

I put a new fuel filter in.. although I haven't really noticed anything with that.. but it was the original filter with 153K on it.. so doesn't hurt.

Anyway, I checked the base timing and it was at only like 8-9BTDC.. screw that.. changed it.. put it up to around 14-15BTDC.. I get no pinging there so I'm happy and it also made the car run so much smoother and it got rid of a good amount of that jerking I was getting at low speeds...

I was still getting this flat spot though in 3rd gear.. it was really horrible.. so yesterday I pulled the air filter out.. had a few leaves in it.. seemed a bit dirty.. well fuckity fuck.. after I pulled the air filter the bitch ran GREAT.. no more flat spots.. healthy pull through the whole rpm band.. that plus it sounds so much meaner lol

Btw, I also ran sea foam through the intake manifold, gas tank and through the crankcase in the oil.. that did help things a little bit... to clean shit out.. but ultimately it wasn't the cure. I also tried a new o2 sensor.. since it was still the original sensor in.. lol that definitly didn't hurt to replace it.

chinaonnitrous1
03-10-2005, 12:02 AM
New things... Pulled a code of 22, 24, and 31. Since I just replaced the coolant temp sensor right near the radiator hose on the motor, I guess that rules out 22.... The intake temp sensor and MAp sensor round out 24, and 31? Correct me if im wrong.


Seems like the MAP sensor is to be at fault. Since all 3 things are tied togehther.

AJz
03-10-2005, 01:21 AM
i hav the same trouble with mine occasionally, its a Jap 2lt 3sge, and i can vouch that the surging almost tinny bunny hops at 55km/h can be annoying, seems to only happen during the first 15 mins before the engine is full warmed up. mine does hav quite a rough idle aswell if its a really cold morning. goes up and down about 150rpm. gonna get the timing adjusted soon, just put in a new K&N panel filter so the airfilters fine. seems to hav calmed it down a bit but is still noticeable.

chinaonnitrous1
03-10-2005, 01:27 AM
i hav the same trouble with mine occasionally, its a Jap 2lt 3sge, and i can vouch that the surging almost tinny bunny hops at 55km/h can be annoying, seems to only happen during the first 15 mins before the engine is full warmed up. mine does hav quite a rough idle aswell if its a really cold morning. goes up and down about 150rpm. gonna get the timing adjusted soon, just put in a new K&N panel filter so the airfilters fine. seems to hav calmed it down a bit but is still noticeable.

mine can get pretty violent at cold, hot, or whatever temperature or speed. Partial throttle at any speed will make it go buck wild.


ANYONE HAVE A MAP sensor for sale?

AJz
03-10-2005, 01:41 AM
yea well as ive heard they hav a tendicy to get quite bitchy sumtime, lol

Punisher
03-10-2005, 02:11 AM
Here are a few things that can be a-miss on the 5sfe.. check your EGR.. remove the vac lines from the throttle body and just loop them on the throttle body.. so the EGR won't work.. that "should" get rid of the bucking while cruising.. also, mark your TPS position then loosen the screws and adjust it.. move it just a tiny tiny bit and rev the engine see how it feels when it idles down.. and you can also check your dizzy timing.. Check your timing with a timing light first with the 2 diag box jumpers shorted out.. that way you can see the actual timing.. then adjust your dizzy.. I have mine over half-way through advanced spark.. and on 91octane it runs just fine.. no pinging.. yesterday, I apparently found a good combination with adjusting the TPS and the dizzy.. runs pretty good now.

I had a bucking issue while in 4th gear and cruising along at partial throttle.. usually puts me around 40mph.. car would buck.. was annoying.. turns out my one EGR hose had a tear in it.. so it kept getting vacuum and losing it.. causing the jerking.

Dr.Auto
03-11-2005, 04:09 AM
Pardon me if I missed anything because I read this really fast. But is it a bucking, or is it actually misfiring, as in perhaps you aren't getting spark to the spark plugs all the time on every firing cycle? I have run into very many drivability concerns like this where it was a misfire that would only show up on acceleration under load. And many times it's just the spark plugs. You said they were just replaced but with what kind? If it has Bosch, splitfire, or autolites in it replace them. Because Toyota's don't like them. And the Bosch is the worst, sometime they run ok on the other two but bosch is the evilest spark plug on this planet when mixed with a Toyota. I garantee that they WILL cause a drivability concern for the vehicle before it's time to replace the plug. When troubleshooting always rule out the big 4 first. Compression, air/fuel charge, spark, and timing (both cam and ign). In this case, knowing nothing about the car I would make sure that the T-baelt was ok and timing was correct (cam and dist). A compression test isn't nessessary considering the condition. Then just confirm that spark is good and also the spark plug. Then go from there as then it get more difficult. but before you spend much more time with it at least check the plugs!

AJz
03-11-2005, 01:42 PM
yea but thats the thing, it isnt under accleration, thats when its fine, its cruising along in 4th with the throttle partially on and it sort "bunny hops", hard to explain really, lol