Alright, I'm in need of some help on this one. My '87 Sport hesitates at various rpm's while accelerating, it'll randomly just cut out or stutter like i'm hitting a rev limiter at verious rpm's, sometimes 3k, sometimes 5 or 4, it's never really the same. I've checked all the normal (fuel filters new, oil change 150 miles ago, no vac leaks, not affected by adding more grounds), it just seems to cut out on me after I set my timing back to normal (was running 15 advanced). Any clues/suggestions?

 

You've probably already been over these, but how about:
Plugs. (I've seen new ones that were bad)
Plug wires. (ditto)
Weak low voltage connections at the coils or ECU.
Bad gas.
A crack in the inlet duct that only opens when the engine torques. (Not just a turbo issue)

 

yea usually if it heasitates while your accelerating your either getting not enough - no gas or no spark or not hot enough to ignite...

anyone jump in if i'm way off

 

Any Error codes? Same symptoms, but I found a warped intake manifold & cracked plastic pipping. It's like disconnecting the TPS for 3 seconds while driving - very bad

 

It seems to be sporadic, changed plug wires, fuel filters new, fuel pump is still chugging along, it's almost like it misses and then catches on the next time around. I checked the plugs about 3 days ago and they were good, power to coils is fine. Really boggling my damn mind!

 

When was the last time you resoldered your ECU?


(trying to think of things that would confuddle a/f/spark...)

 

Never resoldered it, good chance it's dieing on me. Ahh well, time to rip that car apart agian for about the 40th time in the past week...

 

don't know if this is it, but when my water thermo sensor started going on the fritz my car had the same symptoms...

 

He's in Boston and it's February. If the that sensor was dead he'd know it - he wouldn't be able to get the car started. I broke mine last winter and it was a bitch to get her going - couldn't do it without another car boosting mine while I cranked it.

When the sensor dies, the ECU goes into limp mode, and makes the mixture lean (it assumes that it's summer out,) making the car damn near impossible to start in low temps, and it runs like crap until the motor is warmed up to operating temps.

So I'd say his water thermo sensor is fine.

 

agree with you, but if its got an intermittant "open", like mine did it takes on a mind of its own- it'll work great for a while, then all of a sudden while your cruising it'll fail & go into that "limp mode" for a couple of seconds, then revert back to normal again.took me a couple of months to figure it out. All I'm saying is to take a quick look at the connector on the back of the sensor- it'll only take a couple of minutes, then you can rule it out if it's good...

 

uh..i had this problem once...like u can rev it when its in neutral but then when u go it hesitates...i had a aftermarket air filter on and i put stock air box on...its just to much air going in

 

Intermittent... Good point.


I'm just used to completely killing components (I'm really efficient that way.)

 

How were the injectors? Good? Used?