Part-throttle hesitation
Since swapping trannies in my car (to a B15), I've been experiencing increased hesitation under part throttle. I have a '91 SE-R with bolt-ons. I used to get "bucking" occasionally in crawling bumper-to-bumper traffic when I was in first just above idle rpm and light to no throttle. Now I am getting pretty significant hesitation under part-throttle, especially when the car is cold. When I swapped trannies, I went to a lighter flywheel and I don't know if the loss of momentum is making the original problem more pronounced?
I have looked at a lot of hesitation threads and found it can be just about anything. Idle is good, although after going a short bit at part throttle and then pushing in the clutch, the rpms can drop really low (even stalling) before stabilizing at 800rpms. Full throttle is good too.
I recently did a tune-up. Yesterday I pulled the plugs and they looked fine, just a bit used. I used DCScotty's method for testing the MAF, and I think it looks fine. Here's the pic of it:
I am very much a novice when it comes to these things, so please bare with me as I try to implement your suggestions. Thanks in advance!
Edit: The problem is now fixed! I changed a couple of things at once, so I'm not sure which was the culprit. I will outline what I did.
If I had to guess, I'd say that this was the root of my problem:
It had a crack in it and was leaking oil and probably screwing up the air readings. It was located to the right of the headers and went up to the emissions stuff on the front of the engine. Here is the replacement hose:
Other things I did:
I cleaned out the EGR, BPT, and the accompaning metal tubes. Here's a link to a thread with some resources on how to do that:
http://www.sr20-forum.com/general-sr20/23980-can-someone-make-detailed-how-clean-egr-thread.html
Then I replaced all the vacuum hoses I could get my paws on, a few of them looked kind of shady. The last thing I did I don't believe had anything to do it, but just in case, I took off one of the "boxes" that's attached to the intake and plugged it with a 1" PVC end cap:
Now my car is purring. If you have a similar problem, I hope this helps.
I have looked at a lot of hesitation threads and found it can be just about anything. Idle is good, although after going a short bit at part throttle and then pushing in the clutch, the rpms can drop really low (even stalling) before stabilizing at 800rpms. Full throttle is good too.
I recently did a tune-up. Yesterday I pulled the plugs and they looked fine, just a bit used. I used DCScotty's method for testing the MAF, and I think it looks fine. Here's the pic of it:
I am very much a novice when it comes to these things, so please bare with me as I try to implement your suggestions. Thanks in advance!
Edit: The problem is now fixed! I changed a couple of things at once, so I'm not sure which was the culprit. I will outline what I did.
If I had to guess, I'd say that this was the root of my problem:
It had a crack in it and was leaking oil and probably screwing up the air readings. It was located to the right of the headers and went up to the emissions stuff on the front of the engine. Here is the replacement hose:
Other things I did:
I cleaned out the EGR, BPT, and the accompaning metal tubes. Here's a link to a thread with some resources on how to do that:
http://www.sr20-forum.com/general-sr20/23980-can-someone-make-detailed-how-clean-egr-thread.html
Then I replaced all the vacuum hoses I could get my paws on, a few of them looked kind of shady. The last thing I did I don't believe had anything to do it, but just in case, I took off one of the "boxes" that's attached to the intake and plugged it with a 1" PVC end cap:
Now my car is purring. If you have a similar problem, I hope this helps.