Surging 1200-2000 Rpm lite load

**cyeagle** · 07-06-2010, 02:35 PM

Hello to all !!

Been a long time since I've posted here, just have no time like I used to.
Anyway, I've got this lite load surging between 1200-2000 rpm, normal otherwise . Just a crack above idle, and it's getting worse. No codes, cleaned the Maf, new plugs/wires. 70K miles. I'm thinking maybe O2 sensor(s)?
Put my scanner on it today Bank 1&2 #1 O2 sensors are all over the place, #2 sensors are steady. TPS Steady, Timing Etc, steady wtf?

**Cutlass** · 07-07-2010, 05:57 PM

You've made some good repair attempts there. Is it the stock OEM MAF? Does your scan tool read Long Term Fuel Trims? Sounds like its running lean or rich. It is possible for a contaminated O2 sensor to send a false reading to the PCM and cause incorrect fueling to the engine. Other possiblities are low or high fuel pressure, restricted fuel filter, or vacuum leaks.

**cyeagle** · 07-09-2010, 06:43 AM

Originally Posted by Cutlass

You've made some good repair attempts there. Is it the stock OEM MAF? Does your scan tool read Long Term Fuel Trims? Sounds like its running lean or rich. It is possible for a contaminated O2 sensor to send a false reading to the PCM and cause incorrect fueling to the engine. Other possiblities are low or high fuel pressure, restricted fuel filter, or vacuum leaks.

Thanks for the tips ! A buddy called me last night, he asked a Chevy dealer tech (ls1 dude) about the problem and he also mentioned trying the fuel filter first. The MAF is OEM, but I have a temp sensor mod. I plugged the OEM back in and it seamed to make it worse. The mod sensor is supposed to lean out W/O throttle
I'll try the fuel filter this weekend. What fuel press. should I be looking for ? Thanks again

**Cutlass** · 07-10-2010, 04:54 AM

I'd suggest getting rid of that temp sensor mod thing. that can give you some issues also

**Wesman** · 07-10-2010, 06:51 PM

Originally Posted by cyeagle

Thanks for the tips ! A buddy called me last night, he asked a Chevy dealer tech (ls1 dude) about the problem and he also mentioned trying the fuel filter first. The MAF is OEM, but I have a temp sensor mod. I plugged the OEM back in and it seamed to make it worse. The mod sensor is supposed to lean out W/O throttle
I'll try the fuel filter this weekend. What fuel press. should I be looking for ? Thanks again

Stock fuel pressure should be a constant 58PSI.

As Cutlass said, get rid of the stupid temp sensor mod. It only throws off the PCM and skews the readings. I'm willing to bet that's at least part of the problem.