Hope everyone had a nice christmas! I really need some imput on a idle problem and a shaking up through the RPMs. The engine will start idle up to around 1200 and drop back to 750 where it sits for about 20-30 seconds smoothly. After this it starts stumblin down 100-200 RPMs and back. When you throttle up it still has what seems to be a miss or something. When your in gear accelerating you can tell the engine is being held back. I've replaced the fuel injectors, fuel pressure regulator, Main fuel pump and filter. I can here the intank pump whirling, new fuel pump relay, cleaned Throttle Body and new gasket, cleaned Mass Air with mass cleaner. Replaced Cap, Rotor And Wires, new intake gasket and all new vacuum hoses that connect to intake. It looks to have a new RPM crank sensor and Ignition Module. I run 93 Octane fuel from a high volume Chevron gas station and have tried lucas in fuel. I have cleaned and tested the ground wires on the fuel rails and valve cover to body of car to the black box on fire wall. Also, cleaned IAC valve. I have even done the propane test all around the intake and anywhere I thought a vacuum leak could be. Oh yea the head has just been rebuilt and had new spark plugs installed. HHHHHEEEEELLLLPPPPPPPPPP!!!!!!!!!!!!! My wife wants her BRICK back!!!! Thanks. Scoutdad :blush: I've also checked the ECM coolant temp sensor and it works within Specs and had the Battery & Alt checked out. I thought maybe low voltage.

sounds like you have already replaced the entire car!

i noticed the coil wasn't mentioned, i went through a ton of stuff like you did with an obscure missfire problem. after replaceing the coil and really cleaning the wire ends it went away. not sure if you have already done this, but it could help.

i used a coil from summit racing - it was local so i picked it up for $16 - it works great!

http://store.summitracing.com/partdetail.a...15&autoview=sku

Thanks, for the tip. I thought about the coil but just now getting to that. I did discover that one of my refurbished injectors were not working properly. That's where I was getting the miss throughout the RPM range. I still have a idle issue to figure out. Well I plan on keeping this car a long time so the new parts are preventive maint. I'll post back if the coil helps!!!! Happy New Year :clap:

Hi, Have you checked the battery terminal cables. I experienced similar problems last year and noticed voltage was down. I replaced the battery and still experienced similar symptoms. I then checked the cables and found corrosion. I replaced both and it's been running great since. Good luck!

Thanks for the info. I've cleaned and checked cables also. What im thinking is that one of the old injectors is probably not right but it works better than the busted refurbished unit. I should have gone with Accurate Injector Service because they provide a flow sheet of the actual injectors you get back. But the only down side is you have to send them your cars injectors to be refurbed. Or buy their on hand stock at a much higher price. I tried to save money and used someone else. QUALITY COUNTS !!!!!!!! :amen:

I don't know if you've fixed your car yet, but I had exactly the same problem and a Volvo 480 mechanic expalined how to diagnose and fix it.
Disconnect the 12V plug to the IAC.
Start the car.
RPM's will be high ( but not too high)
Re-attach the 12V plug
RPM's will drop
This indicates that the black Bosch switch under the throttle house is working.
The IAC is pretty indistructable, but once it gets dirt, the insides get roughed-up a bit. Cleaning ofter enhances the problem.
Disconnect the top hose and spray WD40 into the opening.
Recconect the hose and start the engine.
Take a pair of pliars and bang agaist the IAC.
If you hear any change in the RPM's, you have found your problem.
Change the RPM's; tap the IAC until it works the way it is supposed to.
This worked for me just this week.
Also, when you're finished, disconnect the + and - from the battery and jump them (the cables) together for 60 seconds. This will reset the computer.
grtz
ER

Thanks !!!! I'll try that :clap:

I'm also having a problem with my 940 93 its rpm is 3000 when I'm driving at 40mph and when it is idle it between 1000 and 2000.. Can you help me figure this out?

Be REAL REAL sure that the spark plugs that were put on the vehicle are the correct ones. Don't be tempted to go for an iridium plug or something of that matter when the coppers or platinums are recommended. a nice set of NGK copper plugs will definately do- my 240 had this problem. You may also look into replacing the Crank Speed sensor- new looking or not, they're not super reliable and are known to go bad- had this same issue with my 945. otherwise, be sure that fuel rail pressure is up to spec.

Good luck!