I have been having problems with a idle surge lately. Changed all the plugs and wires, cap, rotor and still the same thing. A couple times the EEC sent codes out for a lean condition. Could it be the OEM FPR going out even with good pressure with vac off? Noticed the idle pressure seems to change sometimes varying from 32-38. I have a BBK adjustable FPR and thought about trying it out, but I don't want to use if I don't need the extra pressure. Then again at what horse power range is an adjustable one needed. Other than the idle sometimes it jerks a little while driving after a red light when it gets a chance to idle down and start its surge thing, then it clears up and would fly if she had wings...
Surge with idle???
- Thread starter l.groves
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OrangeMustangGt
Founding Member
you know what, my car does that crap also, what i did that helped a little was i turned up my idle, and set my fp at 43.5. it DOes seem fp related though because it will get worse at lower/higher fp'd
is the IAC clean? idle set screw adjusted properly, TPS adjusted after that?
foxes have 10 pin connectors which can get dirty and cause some surging (or the cleaning of them seems to help clear up surging, i should say).
good luck.
foxes have 10 pin connectors which can get dirty and cause some surging (or the cleaning of them seems to help clear up surging, i should say).
good luck.
I tried to increase the idle with the Idle control and the throttle plate in many different ways but the only thing that changed was an increase in surge strength rocking the car pretty heavy. With the idle up it also lingered longer on the run than just at idle. Can't figure it out but it started right before I bought the chip and steadily got worse and occurs almost all the time now at idle. YES- it has a new IAB and TPS is fine, MAF is clean, ECT is new, PCV is fine, Oil is OK, new distrib stator also....
gcomfx.com
Founding Member
No. I haven't pulled the chip since it started doing it just before the chip was installed. The problem started after taking it for a drive and running very rough through all speeds on a quick drive to the store and back. I checked under the hood and one of the plug wires was burnt up on the driver's side header. Fixed the problem but started geting the surge with idle. Don't have any codes showing up on the code reader. I changed the cap, rotor, plugs, wires and stator but same thing. At idle runs rough and when I tried pulling each plug wire it didn't seem to affect the way it ran at all. Runs great driving it's just at idle. Tried unplugging the FPR and it seemed to run a little better. I get 16-17 vacum at the FPR and the pressure is at 42 with vacum off. Vacum on seems to vary from 32-38 but I could have sworn that the pressure was 22 one time with the vacum on. That's why I thought it would be a fuel pressure problem and maybe an adjustable FPR might help or just a new OEM one. My 150 fuel pump is pretty new. I'm also thinking something might have shorted out with the power of the coil running through the headers- don't know what it could be without codes setting off.
I think I searched out the problem through the forums. Ran the car at idle and voltage off charger and battery are fine. Put the car in drive with emergency brake on , lights on, AC on, stereo on and within a minute it started to surge and the voltage output dropped from 14.5 to 13.2, looks like my voltage regulator is going out! I'll try changining it out and write back if problem is solved.
Well it wasn't the alternator, although it helped out with the DC power greatly. I read up and thought about putting my adjustable fuel pressure regulator on. I put it on tonight and so far it turns out the stock regulator was bad and the fuel pressure GAUGE was bad too giving false readings. I'll have to get another gauge to double check but thus far no surge!!! Almost time to down that bud I've been saving for 2 years, hell I'm going for the Guiness if it pans out!!
tonys5.0
New Member
Try replacing the IAC. These things go bad over time and cause exactly the problems you are having.
Turns out the motor was not getting enough Fuel pressure. After I installed an adjustable BBK FPR and increased the fuel pressure no more surge. Needed about 43 pounds to keep from surging and the lean/rich gauge is happy again. Put a new pressure gauge on and same pressure was read. I've heard of other people with similar mods needing increased fuel pressure but most people think stock is fine. So if you have an idle surging problem and have GT40P heads, 24# injectors, cam, and 1.7rr's you may need to increase your fuel pressure. Mine has been running great for days now and I'm not tinkering any more. Feels good to finally be finished to move on to other things.
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