When I'm in gear and my foot is even slightly on the gas the car runs great. In fact, car runs great part-throttle, wot, or whatever. When I take my foot off the gas, and leave the car in gear, it will start "jerking" forward about every second. If I put my foot back on the gas it will stop jerking. If I throw the car in neutral it will stop jerking no matter if my foot is on the gas or not.

The car drives fine, its just really annoying when I'm decelerating to take a corner and my foot is off the gas, but I'm in gear. The jerking problem can be described as just the car lunging (if thats a word) you forward about every second that I'm off the gas.

Before my car got tuned I was running a Crome basemap, stock GSR injectors, and everything ran fine for break-in. After swapping injectors to RC310's and tuned on Neptune is when it started doing this.

If anybody has any experience with this, please help. Someone suggested it could just be a clutch problem. The car wasn't doing this before it got tuned though...I don't understand.

Mods I know this probably belongs in the Tech forum but I just need some fast responses.

TIA
Dinko

 

I had the same prob w/ my car a while back. Replaced master cylinder and that helped out. Might also be a clutch issue. Check out your CMC and see if its leaking at all. From what i've heard, in the older cars, they go out often.

 

My little brother has a jerking problem too.

But for your situation just double check your timing/ air fuel in those specific loads while coasting. Also check your tps and make sure its within spec. Good luck!

 

well i'm wondering if its something within Neptune. is there some "off-throttle" feature anywhere?

i'll check the master cylinder although i don't think that's the problem. last time i checked the fluid in there was at a good level.

flywheel was resurfaced. clutch was used but seemed to be in good condition when we installed everything...

 

this is not clutch, master cylinder or any of that stuff. its something with the ecu programming. I have seen this on several cars, one of them having neptune.

 

Sounds like a timing issue.

In decel, injectors are shut off, and ignition timing is supposed to change dramatically. If the ignition timing is not changed properly, or the injectors arent fully shutting off for whatever reason, The ECU will try and 'find' the sweet spot via feedback from various sensors. Whats still a mystery is why this only started happening when larger injectors were installed.

Wrong impedance injectors perhaps?

 

I have the exact same problem...I though something is grounding or making a short?? and as stated by the OP it only happends when I'm off the throttle and coasting...I then get a CEL code 7, TPS, I replaced it and didnt do it for a long time, but its back!!!...completely stock B16a...I guess any info benefits more than one person so...so guys please let us know any info, knowledge you might have on this....

 

would my tuner be able to tell me anything about this by looking at the file he burned on the chip.

the motor is:

stock b18c1, .20 over RS pr3's, m22 head package, aem short ram, skunk2 IM, stock rail and fpr, rc 310's, megan 4-1, act street clutch

 

help

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Combustion Contraption &raquo;</TD></TR><TR><TD CLASS="quote">
Wrong impedance injectors perhaps?

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i love the title of this thread