Heavy hesitation problem/ power loss

Mr. Griff750 · #1 03-03-2006, 11:20 AM

I own a 91 gst eclipse. In warm weather it hesitates under moderate to heavy throttle and it feels very weak(not near as much pull). On the other hand, When there is cold weather(generally below 20 degrees) the hesitation is almost hard to notice at all and the engine pulls very well. Usually once the engine has been ridden hard a couple times after this, it begins the hesitation problem again. I did a boost leak test and fixed the leaks many months ago and did one recently and all is fine(beside the shaft seal leak but its not leaking enough boost to make a difference.) i have been told that it might be the FPR or timing or just about anything. Does anybody have any ideas of what it could be? Thanks 4 your time.

Blackcrow64 · #2 03-03-2006, 11:28 AM

My guess would be fuel. Maybe its running fine when its cold because there would be more air condensed and the fuel is set perfect for that cold air. But once it heats up and its getting warmer air its running too rich... That would be my next guess if you have no boost leaks.

Mr. Griff750 · #3 03-03-2006, 11:39 AM

Hmm...Do you think that would be the fuel pressure regulator? It does seem like im getting crappy mpg.

Blackcrow64 · #4 03-03-2006, 11:40 AM

What do you have your FPR set to now? Wrong tuning will cause really bad gas mileage.

Also, it helps us know a little more about your car if you put details about it in your signature.

Mr. Griff750 · #5 03-03-2006, 11:53 AM

Well I don't have an aftermarket FPR, just stock. I don't have any modifications other than some "fixes" here and there.

Blackcrow64 · #6 03-03-2006, 12:03 PM

Hmmm... If its stock then I wouldn't see it as being changed unless the stock FPR is going bad. Do you plan on modifying the car or leaving it stock?

Mr. Griff750 · #7 03-03-2006, 12:11 PM

I definitely plan on doin some modifying to it..I haven' yet because ive been trying to figure this problem out. What do you recommend that I do?

Blackcrow64 · #8 03-03-2006, 12:49 PM

Hmmm... Well, if your gonna modify it then I'd say start modifying things that will help the problem for sure... Maybe someone else here has an idea of something else it could be. Thats really the only thing I can think of right now. I'll post back if I think of something else it could be.

blk_srt · #9 03-03-2006, 03:57 PM

Any boost leak is bad, could be your O2 sensor

SLoe · #10 03-03-2006, 06:13 PM

Quote:

Originally Posted by pr_ricer

Any boost leak is bad, could be your O2 sensor

I agree, if it doesn't do it at full throttle. The computer goes into open loop at WOT, and doesn't use the O2 sensor. Also plugs, plug gap, and wires, and IAT sensor could be bad.

Edit: I am leaning toward the IAT, because the problem varies with temperature.

blk_srt · #11 03-03-2006, 06:17 PM

full boost doesn't always equal wot, I had the same problem but it was most prevalent at ~35% throttle going down the highway with the cruise set. Every time I went up a hill it would try and speed up but couldn't, but I had a combination of the 2.

SLoe · #12 03-03-2006, 06:20 PM

Quote:

Originally Posted by pr_ricer

full boost doesn't always equal wot, I had the same problem but it was most prevalent at ~35% throttle going down the highway with the cruise set. Every time I went up a hill it would try and speed up but couldn't, but I had a combination of the 2.

Agreed: WOT has nothing to do with boost. It is based on the position of the TPS.
Edit: I was saying that I agree to the o2 sen. being bad if the problem isn't present at WOT, and I also agree any boost leak is bad.

blk_srt · #13 03-03-2006, 06:34 PM

Gotcha

SLoe · #14 03-03-2006, 07:12 PM

Quote:

Originally Posted by Blackcrow64

My guess would be fuel. Maybe its running fine when its cold because there would be more air condensed and the fuel is set perfect for that cold air. But once it heats up and its getting warmer air its running too rich... .

All that is controlled by the IAT based on temperature

. Not the FPR, it only does what it is told to do. That is why some people relocate the IAT. It makes the comp. "see" colder air entering, and increases fuel to maintain air/fuel ratio. That is why I am convinced it is the IAT more than anything. The other things should be checked too.

Blackcrow64 · #15 03-03-2006, 07:36 PM

Quote:

Originally Posted by loeman

All that is controlled by the IAT based on temperature

. Not the FPR, it only does what it is told to do. That is why some people relocate the IAT. It makes the comp. "see" colder air entering, and increases fuel to maintain air/fuel ratio. That is why I am convinced it is the IAT more than anything. The other things should be checked too.

Ohhh... So I was on the right path but I didn't follow the problem back far enough?

IAT?... Intake Air Temperature? I am still learning all the abbreviations. lol

Where is the IAT located exactly?

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