But only coming off idle. Idles great, accelerates fine under load, except when coming from a stop, and the hesitation occurs before there is a load.

Previously, I checked the TPS with an oscilloscope and found a small interruption right where I expected it, at the beginning of the accelerator pedal travel. It seemed to run better but was not completely fixed. I also cleaned the MAF (and IAC). And the air filter is clean.

But it seems to be worse again, or maybe I only imagined it was better. I don't think it's a fuel delivery issue because I think that would show up under a load. Has anybody seen this before?

 

Could be alot of things

spark plugs, wires, air filter, throttle body is gunked up. the list goes on...

 

Thanks for the feedback. The plugs and wires are new, I cleaned the throttle body and butterfly (forgot to mention that), and the air filter is new.

The interesting thing, is that during acceleration under load, there is no problem--which is when a normal fuel/air delivery issue would present itself. It is only when the accelerator pedal is coming off of it's idle position. Good guess with the throttle body, I wish that was the problem.

 

How old is the timing belt ?

 

The truck is at 130k, so assuming the original owner replaced it at 60k, I'm overdue at 70. Do you think it's stretched or skipped a tooth? It doesn't have any problems under load like pinging or missing or anything out of order. Although it is a little gutless... I thought that was normal for a 2.3, though.

 

the lima has always been gutless, but its the most reliable motor I have come across. I had the same issue recently with the hesitation. New wires fixed it right up. as far as the timing, that would be nice to replace if it is stretching. I never had an issue like that (157xxx miles on the original timing belt before it snapped.lol needless to say the truck was neglected for the majority of its life). also, do you have a stock filter? I had a cheap little cone filter on mine and the power was a little differently distributed (the cone filter always felt like it had no low end power, i don't know if it was because the air flowed differently or what). I have since put a drop in K&N filter in and it seems to be much better. If you have a little cone filter try running a stock filter or a drop in replacement.

 

The wires are pretty new--so I don't think that's the problem. The timing belt is on my to-do list but I don't think that's causing the problem either.

I do have the stock air filter, but I will try to remove it and see if it runs any differently. Thanks for the suggestions. I'll let you know how it goes.

 

did you replace the tps since it had the interuption?

 

Yes, 9 months ago. It seemed to run better for a while, but there is still a serious hesitation, like I'm back where it was before. I rechecked the new one but the resistance changes smoothly, no problems there. I had also swapped in a new MAF (around the same time), which didn't make a difference. I put the old one back in--I can't believe autozone's return policy, but I love it. The MAf is the only thing left that could cause that problem, but I don't want to replace it again without testing it. The 'unplug it and start it up' test only results in the engine quitting.

I was hoping that someone would have had a similar problem with their 2.3, but so far it doesn't sound like it.

 

although i have a 4.0 i had a problem similar to what you described,i took it to somebody and they replaced the fuel filter and maf sensor and it fixed it

 

Hmmm. Fuel filter has been replaced, but it does sound very MAF-ish (new word?). I'll test that next. Thanks for the input.