Rough idle! Think its dumping too much fuel I need help

97ebaygst · Oct 14, 2009

could it be the FPS that is causing to much fuel pressure? I took it off and wired it to a 12v battery and didn't feel anything coming from it, vacuum or pressure. Should I feel either one?
If it is the FPS do I have to have that if I want to run a AFPR? And if I do run a AFPR do I have to have a wide o2 sensor?

97ebaygst · Oct 17, 2009

well I know I said that the alternator was fine the other day but now it took a crap on me. could this be contributing to my problem of running rich? also when I disconnected power to my fuel pump the car actually ran good at idle and I didn't smell any gas at the exhaust. Shouldn't the car idle rough when the fuel pump isn't connected. It's almost like the pump is running to hard and when i disconnected it to depressurize the fuel system it evened out the the load on the injectors. I'm totally lost on what do to. is there a way i can check to see what size injectors I have on the car?

PorkChop · Oct 17, 2009

How about your TPS? Have you checked it? And your BISS screw?
Stock pump and regulator? Pull your injectors, If you look on them they have the number on them like stock ones will have"450" on them.

97ebaygst · Oct 19, 2009

Checked the tps and that checked out fine. biss screw? not sure what that is. The regulator is stock but i haven't pulled the pump yet to see it it's stock, I'm gonna check that next. I'll check the injectors at the same time. If it is the injectors what can i do to fix it other than put the stock ones back in?

PorkChop · Oct 19, 2009

97ebaygst said:
Checked the tps and that checked out fine. biss screw? not sure what that is. The regulator is stock but i haven't pulled the pump yet to see it it's stock, I'm gonna check that next. I'll check the injectors at the same time. If it is the injectors what can i do to fix it other than put the stock ones back in?

Okay if your TPS is good and adjusted correctly then that takes care of that. If it was adjusted too far one way or the other it can cause an unstable idle. I have a 1g throttle body and the screw is on top on the front side ( near the valve cover so to speak, not next to the firewall) It is recessed in there a bit. You made need to adjust it a hair out. If your pump is a 255 then it will over run your stock fpr..not sure how it would affect idle exactly but would highly recommend an aftermarket FPR. Well stock injectors in theory should not give you idling problems. Unless they are partially clogged or something of that nature but then your normal driving conditions would reflect injector issues as well. Do you have an EMS on this? Are you running pump gas in this, What kind of plugs are you using(have you pulled them and are they black with soot?) and what is the gap on them? Tons of variables here!

da_solution · Oct 19, 2009

regarding the dimming and brightening issue with your electronics- have you checked the voltage regulator?

97ebaygst · Oct 19, 2009

PorkChop said:
Okay if your TPS is good and adjusted correctly then that takes care of that. If it was adjusted too far one way or the other it can cause an unstable idle. I have a 1g throttle body and the screw is on top on the front side ( near the valve cover so to speak, not next to the firewall) It is recessed in there a bit. You made need to adjust it a hair out. If your pump is a 255 then it will over run your stock fpr..not sure how it would affect idle exactly but would highly recommend an aftermarket FPR. Well stock injectors in theory should not give you idling problems. Unless they are partially clogged or something of that nature but then your normal driving conditions would reflect injector issues as well. Do you have an EMS on this? Are you running pump gas in this, What kind of plugs are you using(have you pulled them and are they black with soot?) and what is the gap on them? Tons of variables here!

The car idles rough. When I bought it I changed the plugs to bosch plat with the recommended gap. I didn't want to get any better ones incase they got fouled. When I pulled the old ones they were black. I put the bosch in turned the car on and still idle the same, pulled them out after letting it warm up and they were just a black. Like i said in any earlier post my fuel pump is very loud and i don't know if that's normal. I'll pull that out today and check to make sure that its not a 255.

97ebaygst · Oct 19, 2009

da_solution said:
regarding the dimming and brightening issue with your electronics- have you checked the voltage regulator?

It stop doing the dimming and shutting off, but shortly after the alt took a crap and died. I plan on replacing it with one from a 99 galant. I heard that it's a plug and play with more power.

97ebaygst · Oct 20, 2009

well got the alt from the 99 and it didn't fit so got another one from a 96. gonna try it tomorrow and it should fit.

Octane · Oct 20, 2009

I would suspect a noisy fuel pump in turn means its on its way out and that could be contributing to your bad idle, not sure why you would be running rich if its going out tho.

97ebaygst · Oct 20, 2009

Octane said:
I would suspect a noisy fuel pump in turn means its on its way out and that could be contributing to your bad idle, not sure why you would be running rich if its going out tho.

I thought the same thing but I cant think of anything else. I finally got the alt back on it and it's doing the same thing as before. Turning on, rough idle, lights flicker, rev to a grand and shutting off. If I crank it enough times it'll stay on, but it's like 15 times that i have to crank it.
Could a sensor cause this or is my ecu going out.?

Octane · Oct 20, 2009

Id say if you got a friend with the same car just swap them out and even if it doesnt fix it, thats another thing you can rule out. It sounds to me like your turning it on getting spark and fuel then you will give it gas it will get a bit but then it will die out from lack of constant gas. Then when you try and crank it again you wont be getting enough gas for it to ignite and fire up. Its probably not helping your power issue that your cranking it over that long your battery is probably extremely weak, from enagaging the starter. If I were you I would get a mobile mechanic to your house and find out the problem then fix it yourself.

97ebaygst · Oct 21, 2009

I have been looking all over this forum for how to do a fuel pressure test. Basically I want to know what tester to buy and where do I hook it up. Also are there any threads on what parts I would need to do a boost leak test and how to perform one. I have yet to do either one of these and I just want to eliminate them from the list of possible problems.
One last thing, what sensors would control the amount of gas that get dumped into the cylinder. I remind u it does it when cold too so I would assume that the o2 sensor and coolant temp sensor would not cause it because its on the closed loop circuit until the car heats up.
My list consist of....
1.tps
2.mas
3.mdp
4.cam angle
5. was wondering if the crank angle sensor could cause to much fuel.
did I miss any?

97ebaygst · Oct 23, 2009

I was under the hood of my car trying to take off the tps (to no avail) when i notice a plug dis-connected, well I did some research and found out that it is my knock sensor unplugged. I can't find the knock sensor plug in. So I have two questions.
1.could this be a possible cause to the fuel dumping and the cut off problem?
2.where is the knock sensor located? I know it's on the back off the block somewhere but I was hoping for some more detail like which side would be easiest to find it, is it high on the block or low?
Oh and one more question what kinda symptom would you get from it not being hooked up.

97ebaygst · Oct 26, 2009

well i found the knock sensor plug and hooked that back up. I decided to test the tps by disconnecting it and found that the car idle better but it would only let me rev up to 2500 rpm then it would start to back fire. Is that a sign that the tps is going out? doesn't the computer run in limp mode when it see's that its not hooked up?
I plan on finding a tps to put on but I can't seem to manage to get the old one off. The intake seems to get in the way. Anyone got any advice on how to take one off?

yeahitsaturbo · Oct 26, 2009

When you statr the car does your CEl come on and then go off or does it not come on at all? If it doesn't come on at all it more than likely the ECU, meaning the CEL bulb burned out. If you can get your hands on a OBDII scanner then try that or just pull your ECU and look at the insides for leaking capacitors and/or a fish smell.

97ebaygst · Feb 18, 2010

well i know this is an old thread but inc ase it helps anyone out the problem ended up being that the previous owner f**ked the wiring to the front o2 sensor and the wires kept touching which in turn kept blowing the ecu ground which made the tps look like it was wot the whole time. solder a small piece of 20 gauge solid wire I bought from radio shack and presto car runs good.

Rough idle! Think its dumping too much fuel I need help

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