Engine RPMs go Up and Down - Urgent please

[Moe Arif]

89 Honda Civic 3 door hatch 1.6 lit. - Only when car is driven for 20 minutes or so, and kept either in Park or neutral, the RPMs go high and low, in a repititive fashion. Just like the car is in park mode and someone is accelerating and releasing in a cyclic fashion.

This started to happen about 3 weeks ago. Otherwise the car drives very well.

[thefooshmeister]

what rpm is it movin up and down thru..when idling mine sometimes moves about 100-200 up or down. i kno its from a vacuum leak somewhere..i just need to find it

[FrodoGT]

Sounds like a vacuum leak, or your EACV. Do a search and youll learn tons as this is a common problem on these cars.

[Moe Arif]

Between 1200 and 1300 RPM. Normal is 900 RPM.

When it happens, opening the hood seems to be a bit hotter than before (not sure). Thought it was a vacume leak somewhere. Is there a test I can do to confirm.
My mechanic friend says it is fuel related. Mine is automatic, it simply revs up, otherwise (if manual) it would have stalled.
ANY suggestions as to how I can confirm between fuel and vaccum issue.
Thanks.

[FrodoGT]

Well since its an auto when its in drive there is a load on the engine and it wont surge up and down like if it were just idling. Are you throwing any check engine lights? look under the passenger side carpet and look in the little hole on the ecu, are there any blinking lights? if so, how many? count the blinks, if there is more than one code it will pause in between, then repeat.

[viper-blue]

like frodo said check for codes...if the system can't maintain proper fuel pressure it would cause the syptoms you have, but these cars have fuel pumps that just won't die...any fuel odor around the car?

[Moe Arif]

My mechanic friend did some tests and said its my Fuel Injectors gone bad. They are costly @ $400. Mine has two of them. Dont have this kind of money. Any advise.

Should I take a second opinion?

[FrodoGT]

What kind of freaking solid gold injectors is he talking about?! thats crap..if you think its your injectors go pull a couple from the junkyard and call it a day, they arent hard to install.

[Moe Arif]

That's good to know FrodoGT. Roughly what would be the cost of a FI be, used and new.
Sounds like it may be affordable to me, in which case I will try installing it myself (if you say it not too hard) - Have any instructions? diagrams?
Thanks.

[Kunundrum]

Doe sit do it whwen the car is cold or only when it's warm ? if it only does it when it's warm it could be cause by a dirty FITV (fast Idle throttle valve) use take it appart, and wash it with break cleaner.

[FrodoGT]

The FITV is for cold idle...the EACV or IACV (same part) is for warm idle. Also, d series dont have a FITV..b series do

Have you checked for ecu trouble codes yet?

[viper-blue]

if the mechanic said it was injectors I would definately just use junkyard ones. You don't wanna spend all that money to find out that the injector wasn't the problem. It sounds doubtful if the problem only happens when the engine warms up. You should check the codes yourself. Do a search on checking for engine codes. Its easy. The mechanic might be trying to take advantage of you at that price, lol. Sounds like dealership prices. Replacing them is self explanatory if you just look under the hood

[thefooshmeister]

yeah you just disconnect your fuel line from the pump and leave it attched to the fuel rail. then unbolt the fuel rail and pop out your injectors. shouldnt even take you an hour to fix. you could try cleaning them but the car is old so you might as well just buy some new ones off of ebay or junkyard them..pm me and ill send you the shop manual if you dont have one

where you been kunundrum?? havent seen you on here in ages

[CRXperiment]

Originally Posted by thefooshmeister

yeah you just disconnect your fuel line from the pump and leave it attched to the fuel rail. then unbolt the fuel rail and pop out your injectors. shouldnt even take you an hour to fix. you could try cleaning them but the car is old so you might as well just buy some new ones off of ebay or junkyard them..pm me and ill send you the shop manual if you dont have one

where you been kunundrum?? havent seen you on here in ages

His car is dpfi, so no fuel rail. Before even replacing the injectors (they rarely ever go bad on these cars) do as Frodo said, his advice is gold; even better than your mechanics'. Clean your IACV, its not hard at all, take it off, get some carb cleaner and soak it clean. 30 mins tops and your problem is likely to go away, try it out before doing some costly repair.

[thefooshmeister]

my bad lol