Idle jumps from 1200-1600

[suprafreakz]

Hey guys.... I just purchased a 1989 240 hatch w/ an rr20det...I was very impressed with its power and look however it has an idle problem that is pissing me off.... I can't seem to fix it..

the idle will rev to about 1600 at start up and then hop between 1200 and 1600 back and forth.... Also if I am running above 80% throttle it stutters a bit and loses power til I let off the throttle a little... any thoughts or help will be appreciated.

thanks:help

[xxtrizz]

I dont know about the RB series but you might decided to check the standard issues with any idle problem.

vacuum hoses, EGR, Idle controls, MAF, or ask the guy you bought it from and tell him if he doesnt fix then you will slaughter him with your spoon.

[elwesso]

I woudl say a vacuum leak.....

Is the IAC adjusted right??? I would however lean more towards a vacuum leak..

A good independent shop should have a smoke machine to find leaks. They hook it up to the plenum, it pressurizes it and smoke comes out wherever a leak is... Makes life SO much easier!!

You might try using some WD40 with the engine idling and spraying it to see if it changes the idle speed...

IT could also be a sticky TB, it would be a good idea to clean it out anyway.. Al kinds of crap gets built up in there and could cause the plate to stick partially open.....

[Altiman94]

could be your coolant temp sensor as well

[spec-u-later]

Yeah check the vacumes. If the idler vacume is not hooked up right you can get that on any kind of motor. My KA did it.

[elwesso]

A coolant temp sensor should throw a CEL.....

[suprafreakz]

a coolant sensor would cause that? It goes to the shop on thursday and ill post results then.

what about the stutter @ wide open throttle?

[elwesso]

When you say shudder, could you be a bit more specific...

It sounds like for some reason the car is flooding (like the old carb engines when you give it too much gas too fast)... Maybe an injector problem or something, this could be hard to figure out...

If its going in the shop we'll wait for the results...

[S13240]

Fuel pump upgrade?

[suprafreakz]

yeah, the guy put on a walbro 255..... do you think that could be the culprit?

[elwesso]

I bet thats it..... Dang I havent realized that you 240 owners have one hell of an aftermarket...

Get the stocker back in there and I bet all will be good!

[SpeedRacer1]

Do you have a BOV? Some SR's with BOV's and preset higher idles will stay up at 14-1600 RPM's until the car comes to a full stop. At least thats what my car does whenever the BOV is installed. Also if the BOV is too loose it will vent the air at 80% throttle, thus the shuddering may occur because the air that was supposed to go into the cylinders is now floating around your engine bay.

Also on a relatively stock SR, if the idle is set improperly (aka wrong level) the idle will idle hunt, have high or low idle, and have a lack of power/poor acceleration. The same symptoms can be caused by the TPS being incorrectly adjusted. There is of course the chance that the ignition timing is slightly off, so be sure to check that too.

The coolant sensor would be last on my list of stuff to check since it doesnt result in the symptoms you named.

Just a thought assuming you meant to type SR20DET and not RB20DET.

[S13240]

yeah, the guy put on a walbro 255..... do you think that could be the culprit?

Nope that walbro fp is not the problem then. Perhaps your problem lies elsewhere with the car. Idle hopping could have something to do with a sticking throttle body, tps, and or idle air control valve if the rb20 has one which it should...probably dead or malfunctioning.

[suprafreakz]

I appreciate all of your guys input.... nothing against my home forum but my threads here have gotten great feedback and there is definately alot less flaming occuring on these boards...I will be checking this situation out fully and should have the old girl running good soon.

thanks again, Ryan