My daughter's fiance has a series 1 NA 3800 Olds thats having a rough idle and hesitating at various speeds. I did a scan while the were over and there are no stored, active or pending codes and I could use some help interpreting some of the results


The TPS voltage seems low to me, 0.29v at idle. Is that S1 normal or should this be ~0.45v

The O2 cross counts seem low, at 0 to 3 (at idle). I would think this should be much higher.

Coolant Temp is steady at 90 degrees even though the gauge reads 190. Where about is this sensor located on the S1?

and lastly the Maf is reading 4 to 5 gr/sec at idle. What is normal for an S1 na?

I have more data if its needed

Thanks.
Tim

Hi Tim,
I think you're correct on the TPS voltage but don't think that would cause a rough idle.

S1's might have 2 temp sensors, one for the gauge & another for PCM. Are you sure the scanner wasn't giving the temp in Celsius? 90 Celsius = 194 F.

Someone else will have to give you the answer on the MAF & O2.

_________________
2006 Chevy Monte Carlo SS

What year is the Olds? And were there any other issues you noticed? Depending on the year the O2 can be a 1 wire, 3 wire heated or 4 wire heated...

4-5 on the MAF is normal at idle..

The TPS is a hair off, .36-.45v should be the target area.. If this is an older system its possible that it could cause a quirky idle..

The Olds is a 93.

good catch on the celcius Mike, that was it all right. I put it to Fahrenheit and got 196.20

So its down to O2 sensor, if that cross count isn't normal. O2 sensor voltage switches between 57mv and 809mv btw. And I'll clean the IAC too to see if that helps the idle.

Thanks,
Tim

no work done today. I had a 9am interview and while I was there he was taken to one of the hospitals for a possible heart attack. I've no news yet on his condition. He wasn't taken to my hospital :(

He's ok. They beleive it was stress at this point.