Hesitation Quizzy

[Sonicfrog]

Lets say I am a $500 87 T-Wag named Murphy and I have a problem. When my driver accelerates lightly, I bog down a bit, but not always. If he gives me more gas the problem goes away. Once I get up to speed, say 2800 RPM, the problem seems to go away. It almost seems like I can't decide what to do. Every once in a while, the problem is pronounced and even flooring it doesn't help. My wonderful owner will let up on the gas to conquer my bout of hesitation. This only happens when the engine is warmed up. What problem do I have???

[Syonyk]

Clogged fuel filter, bad fuel pump, bad coolant temperature sensor, bad throttle position sensor, ignition timing off, bad spark plugs/wires, clogged fuel injector...

 

Any of these could cause it.

 

What have you done so far? Cheap things would be spark plugs, spark plug wires, cap/rotor, ignition timing, fuel filter. If you haven't done those, it's probably worth doing them anyway.

 

Then, you can fairly easily check the throttle position sensor & coolant temperature sensors with a voltmeter.

 

Beyond that, good luck :-) Cleaning the injectors (taking them out, sending them in) & a new fuel pump might be in order.

 

-=Russ=-

[Sonicfrog]

Clogged fuel filter, bad fuel pump, bad coolant temperature sensor, bad throttle position sensor, ignition timing off, bad spark plugs/wires, clogged fuel injector...

 

Any of these could cause it.

 

What have you done so far? Cheap things would be spark plugs, spark plug wires, cap/rotor, ignition timing, fuel filter. If you haven't done those, it's probably worth doing them anyway.

 

Then, you can fairly easily check the throttle position sensor & coolant temperature sensors with a voltmeter.

 

Beyond that, good luck :-) Cleaning the injectors (taking them out, sending them in) & a new fuel pump might be in order.

 

-=Russ=-

Cheap stuff on list are replaced, with exception of fuel filter, thought I think I did replace that a couple of years ago. But it doesn't sound like that to me as usually a bad FF will be more evident at higher RPM's when more gas is needed for combustion. The problem is an intermittent dead spot on acceleration just off idle. Sometimes it feels like a nut! Sometimes it don't! (Mounds, Almond Joy commercial).

 

Coolant temp sensor was replaced recently.

 

I'm kinda leaning toward a 1/2 clogged injector, or the TPS. Which leads to my next question. Where is the TPS located on the EA82T, and what is the procedure for checking it? I am quite handy with the multimeter (repair spas) so don't be afraid to get technical.

[daeron]

the FMS lays out procedures for testing each and every component of the FI system (turbo and non) individually.. pm me with your e-mail address and I can email you the two acrobat files that float around. it isn't the whole thing, but its the engine chunk at least. Useful, to say the least.

[GeneralDisorder]

the FMS lays out procedures for testing each and every component of the FI system (turbo and non) individually.. pm me with your e-mail address and I can email you the two acrobat files that float around. it isn't the whole thing, but its the engine chunk at least. Useful, to say the least.

 

Actually - it's not all there, and the missing part is (drum roll)....... MPFI turbo troubleshooting section :-\

 

GD

[daeron]

Actually - it's not all there, and the missing part is (drum roll)....... MPFI turbo troubleshooting section :-\

 

GD

 

I need a foot-in-mouth emoticon

[86subaru]

clean the idle air control , or tps , it really helped my 88 turbo , mine had the same problem ,

[robm]

Cleanng the MAF may help, too.

[Sonicfrog]

Well, I have beaten the problem... mostly.

 

First off, when I timed the ignition, I screwed up. I thought I had read somewhere the ignition timing was different, depending on the type of tranny in the car. The crappy 3 speed was set at about 20 BTC, and I thought that the manual trannys were set at 10'ish. On a whim, I thought I would double check that idea, and I found I was wrong. So now the timing is set to 20. This would certainly explain the lack of power at low RPMs.

 

I cleaned the MAF sensor with spray electric contact cleaner cleaner, and cleaned the terminals and plug on the TPS. The TPS plug had quite a bit of corrosion on it. I still get a bout of hesitation every once in a while, but the acceleration is much smoother. I don't get that surging / accel stepping feeling, the car accelerates evenly now. I do still get that hesitation every once in a while, but otherwise, the car is now driving like a the little rocket I expected when I swapped the crappy 3 speed auto with the FT4WD 5 speed. What a fun car Murphy has become. Now if only I could fix the tranny leaking on the exaust so it would stop smelling.....

[daeron]

Need brooks no delay, yet late was better than never. I emailed you the FSM about half an hour ago, but congrats on your repairs. just about ANY FI vehicle this old needs this kind of tune up and sensor check. Thats what the FSM is great for.. if you have all the info. apparently, tho, GD says the troubleshooting section on the turbo wasnt there.. I know it has some of the turbo information because ive had to skip past it in reading...

 

anyhow, I still envy you for your 5-spd swap. no time, no money, no donor car here. 3AT == suxx0r..