Poor acceleration (1 Viewer)

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Joined
Jan 1, 2009
Threads
8
Messages
59
Location
Columbia, SC
1997 FZJ 80 145k miles

About 1 month ago I cleaned my MAF sensor because I had an intermittent miss at idle and around 1800 RPM while driving. Everything was fine for a day, until the miss came back along with code po120. The 80 also began to accelerate poorly when cold. After it warmed up, the acceleration seems fine. I checked the resistance of the TPS according to the FSM and it was still good. I cleared the code, and it came back with the same symptoms. I cleaned the MAF again, which helped, and the symptoms came back.

When it is cold and I put the gas to the floor it poorly accelerates. If I manually change the gear selector from D to 2, it downshifts and accelerates well. Using the PWR button does not change anything. Turning on and off the OD button does not help. When on the highway and giving it gas, the trans will down shift, so I don't think it is the kickdown cable.

Do I have 2 different problems? Am I looking at a trans problem or is the TPS bad, but not bad enough to be out of specs?

TLDR: My 80 accelerates like a turn when cold. It throws TPS code for a TPS still in spec
 
Did you recently clear the comp just before it started missing?

I think all new vehicles have "conditioning" settings that need to be reset after comp reset. My moms corolla does it every year when the outside temp is 45 deg different from the coolant temp.

All these have to be run with no CEL on, so disconnect neg, and turn key to on for two mins before attempting.

Toyota Corolla Repair Manual: Readiness monitor drive pattern - Sfi system - Diagnostics


This may be yours

www.toyotaparts.metro-toyota.com%2FREADINESS_MONITOR_DRIVE_PATTERNS_T-EG02-003.pdf
 
Last edited:
There were no codes when the miss was present.
 
Since the PO120 code keeps coming back you may still have a problem with the TPS circuit. But before you spend any money on replacing parts, first try the free stuff, like cleaning the built up carbon out of your throttle body, then reset the code. If the code returns take a look at the TPS sensor for a poor electrical connection at the switch, look for bent pins, or corrosion on the connector pins. Next, using you multimeter check to see if the TPS circuit is open, or shorted. If that still doesn't solve your problem, you may need to replace the TPS switch, but like i said before, try the free stuff first.
 
Did you recently clear the comp just before it started missing?

I think all new vehicles have "conditioning" settings that need to be reset after comp reset. My moms corolla does it every year when the outside temp is 45 deg different from the coolant temp.

All these have to be run with no CEL on, so disconnect neg, and turn key to on for two mins before attempting.

Toyota Corolla Repair Manual: Readiness monitor drive pattern - Sfi system - Diagnostics


This may be yours

www.toyotaparts.metro-toyota.com%2FREADINESS_MONITOR_DRIVE_PATTERNS_T-EG02-003.pdf


I tried this and no help code was still present. I did notice that the PCV grommet was torn (after only about 2000 miles). I replaced it and it did help with the idle. I started the truck cold, and it did not immediately throw a code, it waited until I left the drive way. The PVC grommet replacement did help with the erratic idle. Its been pretty warm here the last few days (South Carolina) and the code has been less frequent. The acceleration problem has helped.

I will try checking for a short here in the next few days. The AC also decided to go out as well today, just in time for the 90 degree weather to show up this weekend.
 
I had a few days of problem free driving with my 80. My wife had to drive the 80 for a day, and of course the poor acceleration and TPS code came on when she drove it. I cleared the code and had 3 more days of code free driving. I blame the wet weather we had the last 2 days and also had time to check the TPS circuit. All good. I rechecked the TPS switch, and sure enough its out of spec. I replaced it tonight and will monitor the next few days and see what happens.
 
Alright after a little incident with a radiator replacement I've had the chance to fully assess my acceleration problem. Since replacing the TPS, I have had no problems with a miss, no problems with idle, and the 80 is accelerating as well as it can. It feels like riding a puma at this point, compared to how it was running.

I appreciate the recommendations, and hope this helps someone in the future.

On to the next project!
 

Users who are viewing this thread

Back
Top Bottom