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need help w/partial throttle surging

9

95pgt-t

Hard-core CEG'er
Joined
Nov 20, 2006
Messages
3,163
Location
oneonta,ny
first off,i've read all the threads i could find under surge,or surging.
i've changed the plug wires twice w/known working wires,and once w/brand new. changed the plugs and gapped them,changed and cleaned the maf twice w/working maf's,new fuel filter,cleaned the egr,iac and upper and lower manifolds,swapped tps'...basically i've done everything i can think of,short of changing the coil and fuel pump.

by changing those parts all i did was move the surge from 2750 to 3400:shrug: i'm getting no codes,and have no pending codes:shrug:
basically it runs smooth under wot in any gear at any rpm, at any load. but if i'm accelerating at partial throttle,say less than 50% it surges or bucks at 3400~ and than again around 4k(only if i stay at that constant light throttle)if it bucks at 3400 and i put the pedal down,it's smooth again:shrug: i'm at my wit's end.
btw,its a early 99 svt
 
Test your throttle position sensor (TPS), check in a repair manual for proper testing.
 
hahaha
boot.gif
 
yeah,i followed that thread before i had my issue's...mainly b/c of who it involved:laugh: my linkage is all there,and when i rev the car i can watch it open..i'm going to swap it out the box soon though just to make sure.
 
mine acts very very similar to the one in the thread. also mooses once in a while. was that his cure? LIM linkage?
 
oh
my bad...mines got good top end. just a real bad "flat spot" in the 3-4k rpm range. and bucks/surges at low rpm's (like crawling in 1st gear) but will come out of it with a shot of gas w/the clutch in. also mooses once in a while.
 
nah..compression is well within spec:cool:
i figured it out..its smooth again...my imrc box is shot though. it opens..but closes right back up:blackeye:
 
well,that doesnt explain the bucking..that just explains the lack of pull or audiable sound i was missing,as stated in the "problems w/ebay maf adaptor" thread i made.
as far as what changed the surge..no real clue,i removed the sock on the fuel pump,cleaned the egr/pcv ports in the manifold,new plugs,wires and dil. grease on the coilpack harness and all sp's and wires,replaced all rubber vac lines,cleaned ground contacts,bored the ebay maf adaptor out and cut a notch for the sample tube,cleaned the lim and tb too
 
Funny, been dealing with the exact same issue for a while.

Solved mine over the weekend... I pulled the vacuum line off of the EGR. Night and day difference. No surging/bucking. Strong smooth acceleration. I have plugged the vacuum line for now and am enjoying the piece and quiet again.
 
i sprayed some brake cleaner in the manifold inlet port for the egr while i was doing this...so maybe thats what it was:shrug: can't tell ya,i started doing things one at a time to troubleshoot...than i just did everything all at once.
 
95pgt-t said:
i sprayed some brake cleaner in the manifold inlet port for the egr while i was doing this...so maybe thats what it was:shrug: can't tell ya,i started doing things one at a time to troubleshoot...than i just did everything all at once.
Click to expand...

I remember a IMRC how-to that acutally was a great way to fix the boxes. I know i saved it, or printed it. If you do search it will be on the old forums for sure.
 
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