I recently had serious problems with my vehicle dying for unknown reasons. I replaced the rpm sensor, fi relay, radio interference relay and power stage. I cleaned out the throttle body and reset the throttle position sensor, as well.
Now when im driving the car runs well, but it surges. the rpms seem to increase and little and go back to normal. mostly in the 2000 rpm area and 3500 rpm area. The car also seems to have little power in the 1500 rpm range, sort of stumbles but if you accelerate a little harder the rpms rise and it has normal power. Well if anyone has suggestions they are extremely well appreciated. Thans for all the previous help too, guys!

Thanks in advance,
Fred

Greetings,

Sounds a lot like the problems I had a year ago with the IAC valve. Check out the FAQ's. With mine the problem with idle surges started after I cleaned it. Perhaps the only thing holding it together was the dirt. Wrestled with the trottle body, idle settings, throttle position switch etc. Finally ordered a new IAC valve and problem solved.

Mike

1994 940T 109k-miles

ITS A NON TURBO 940 SEDAN, I ADJUSTED THE TPS ACCORDING TO THE INSTRUCTIONS IN THE faq, BUT ILL DO THAT OVER JUST IN CASE. ILL CHECK FOR VACUUM LEAKS IF ANY ONE HAS A GOOD WAY OF SEARCHING FOR A LEAK LET ME KNOW. iM ALSO NOT GETTING ANY CODES ALL 1 1 1

What is the possibility you got the TPS misset and it it telling the IAC system to control the RPM while you are running at light throttle?

Just an idea.
--
'96 965, 16' wheels, rear 18mm bar & Koni + 204HP cams at 125K. Had '85 745 Turbo Diesel for 200K.

Is this a turbo or NA engine?

Dear Fred,

Good a.m. and may this find you well. What, if any, On-Board Diagnostic (OBD) codes are displayed? The code readout boxes are mounted on the driver side strut tower (USA/Canada models). Box A, position 2, will provide information about the health of the fuel injection / engine management system. See the FAQs, under FEATURES, above, for instructions on accessing these codes.

Please post back, with your findings.

Yours faithfully,

spook

Sounds like you might have a vacuum leak...

Yeah, good one Paul. When REPLACING all the lines also look at the hard to get to fuel vapor canister lines too. He should also check the block off plug there. Could be the infamous intake manifold gasket.