jbrob007

I've read through MOST of the "surging" threads that involve a surging IDLE, RICH mixture, BLACK exhaust, etc... My car doesnt have any of those symptoms - it idles smooth, starts every time, etc, but surges hard when at light throttle. Doesnt matter if its hot, cold, warmed up or just finished a 200 mile jog. It is much more noticable in lower gears & can surge badly if you dont push in the clutch or give it MORE gas, but you can feel it in all gears when running with a light throttle. I have the idle set at approx 750 - 800 rpm & it sits there like glue.

Edit: The surging may be related to the flat connector (3 prong I think) at the front of the engine. The connector got knocked around during intake refresh & wants to crumble in my hands. From what I've read in the other surging threads this is the connector to the Throttle Position Sensor (TPS) - correct?

Would a bad or spotty connection have this result?? Also, if this is the culprit... how the hell do ya fix it? The other end snakes into a bundle of electrical wires that dissapear under the intake and back into the car never to be seen again... I'm hesitant to mess with it...

Any clues, suggestions, advice is most appreciated.

Thanks in advance,

Joel

PorKen

Surging can be from being too lean. How old is the O2 sensor?

Can also happen from too much ignition advance at part throttle.

Did it happen with stock chips, too?

SMTCapeCod

How about vacuum leak...split connector on a small line probably wouldn't give you big surge- how's your plastic v tube for intake/brake booster? Intermittancy is tricky.

PorKen

Also check the ignition amps up near the front bumper. They both have to be Bosch in order to run non-resistor plugs. With Huecos, I had odd part throttle behavior, but also an idle problem.

I don't like the Hueco aftermarket type, regardless, because they don't appear to be as well made as the (more expensive) Bosch.

jbrob007

Ken,

The O2 sensor is probably stock (59K miles). Didnt happen with stock chips that I noticed... or it runs soooooo much stronger now that the surging is MORE noticable. I have the 3.5 version chipset with stock H pipe & O2 sensor into dual exhaust, dual cats, both intermediates & a RMB. It is running on 89 Octane with the "lean mode" connectors plugged in - should I unplug as a first step in trouble-shooting then move on to the O2 sensor??

This just occurrec to me since I just finished driving it 300 miles... Would a too lean mixture also have the symptom of "lifter clacking" at WOT out of the hole? That would explain a lot. I also have a LSD if that makes any difference.

I wouldnt know too much ignition advance from too little... or how to correct it Thanks again!

Joel

jbrob007

Just finished an intake refresh - replaced all the vac lines I could get to including the v tube with a brand new connector.

Thanks,

Joel

jbrob007

Ken,

I'll need a picture of what your talking about since I have no idea what your talking about... Everything looks to be original. The previous owner was not in the habit of replacing parts with something that wasnt stock! I gotta say, he's probably one of the best POs around Still, I'll check to see if anything looks out of the ordinary or a replacement part.

Joel

PorKen

Probably a good time to change the O2.

Pretty sure what you are hearing is ignition knocking, not lifter noise.

This means you are running quite lean. Mostly likely from a bad or incorrectly adjusted MAF sensor. Could be low fuel pressure. Could be the WOT switch is not working, or it's not connected to the LH.

Check the MAF CO adjustment at the LH plug between terminals 14 and 25. It should normally be around 382 ohms.

Check the WOT switch between 12 and 25. Should show no to low resistance with the accelerator almost to the floor.

EZ/LH pinouts - (EZF_LH22_32V.pdf)

jbrob007

Ken, You just left me at the corner store... tech wise... this is SO far over my head. I'll see if I can get anybody around here that knows how to do this without frying something.

In the meantime, the ignition amps are good. So, I disconnected the battery, disconnected the "lean mode" connectors on the LH computer & reconnected the battery (which should reboot the computers - correct?). Then I started her up... good idle right at 750ish... and took her out for a test drive and an old fashioned Italian tune up. The surging is ALMOST gone. Its still there a little, but not nearly as severe... I figure the lean mode is probably aggravating an existing condition. I'll keep them unplugged until I figure it out...

Thanks,

Joel

jbrob007

I'll start with the O2 sensor... most likely the cause as I'm sure its the original issue and easier to do with limited tech knowledge

Thanks for the guidance