unable to figure out help

[ownonly187]

i have a 87 with a 29 and i cant seem to figure out why my idle will not steady on a cold startup untill it warms up i cleaned out the egr and got new valve but it gums right up and i just found a break in my vacume line leaving the egr will that vacume cause this unsteady idle or am i missin somethin else also i got alot of blowback whats the cause

 

[Cyberbeer]

Any break in vacuum will make it idle erratically. Usually its like a surging...revs up, goes down, revs up, goes down. Fix the leak and check it again, could be just that simple.

I'd also check your PCV valve..and breather cap is so equipped.

 

[ownonly187]

ok well how bout the blowback cuz its got a new pcv valve

 

[IMenriched]

ok well how bout the blowback cuz its got a new pcv valve

Blowback or blow-by is generally caused by rings that are not seated or more likely rings that are worn...or gummed up with deposits not letting them fully seal....in effect, letting some of the compression sneak by...the PVC just allows this to vent off the internal pressure. Poor valve seating or stem seal can do the same.

Have you done a compression check??

ALso remove & clean the AIC (passanger side of the upper intake, about midstream)...it also helps idle if it is carboned up, & internal rod isn't allowed to move as needed it will cause poor idling.

 

[ownonly187]

so is rebulildin the the best option if i got bad rings....like will it be worth it in the long run bc its only got 93000 orig miles and idk if i should wait or go ahead with the rebuild

 

[IMenriched]

so is rebulildin the the best option if i got bad rings....like will it be worth it in the long run bc its only got 93000 orig miles and idk if i should wait or go ahead with the rebuild

I'd try a oil flush 1st before getting too carried away. it maybe just gummed up with carbon/sludge. with a good oil flush & filter and repeat 2-3 times after 200miles for each. check the compression before doing the oil flush and recheck after doing so you can gage the effectivness.

have you replaced the plugs and wires???

 

[holyford86]

About the only thing you should use to clean out your engine is clean engine oil. Flush kits can break big chunks loose and clog your oil sump with crap. Compression test your engine and pull codes (instructions in the tech library). Check for vacuum leaks and clean the IAC. If you have low compression and it is ring related then you would need a bottom end rebuild, top end rebuild is intake and heads.