Re: 91 Sentra 1.6 stumbling on acceleration final round-

Well... I thought I was finished... The replacement distributor did help a little *i think* but did not eliminate the symptoms entirely. It seemed there was some small increase in power there- I also pulled the power transistor that is in the circuit for the distributor- it tested fine but I swapped it out as well.,, no change (as expected) Reseated the ECU - I noticed no corrosion on it. I'm back to wondering about the MAF - and as someone mentioned a while ago- O2 sensor? biggest symptom - stumbling on initial acceleration, about 1/3 throttle- goes away if you let off and then apply slow stready throttle. prior checks- PCV valve, all vacuum hoses, EGR, IAC, replaced temp sensor for the ECU, TPS, distributor, and power transistor,,, Thanks again for any contributors- Robbie

I will post a final update after I drive around tomorrow, but i'm giving a tentative problem solved for now- I found a post on a nissan forum (somewhere) with a 1.6 liter with my exact symptoms that was cured by a good cleaning of the IAC valve assembly. I took mine off and didnt actual disassemble it- it really didn't look that crummy- but it did have a little carbon on it. After a thorough cleaning and re-install i have ALL the power back, and the hesitation/stumble has disappeared. seriously. From cold start to normal operating temp, it ran flawlessly. (Well, it ran GREAT- the engine has 224k miles on it!)

I had NO idea a little dirt could cause such trouble, but I am a believer now. If the problem recurs, I will be back, but for now- all you Nissan owners- a performance problem for the 1.6 COULD be a dirty IAC valve!