Need help diagnosing 2 problems...

[Cobra-21]

OK, got 2 problems that came up about the same time. (2004 Cobra, 47K miles, mods in sig).
1) A/C, vent, etc. blower only works in the High speed position, not in any of the lower fan speeds. A/C cools fine, just can't adjust the fan speed to anything less than High. Is there a fan switch/module that would be the culprit? How hard to repair myself?
2) Got a miss at idle. Also noticed the idle seems to hang higher than usual, maybe 900-1000 rpm instead of 750. The Check Engine Light is not lit. New TR6ix (.032 gap) installed 3 months ago, never had a problem with these before. Also recharged my air filter same time and changed the fuel filter. Ran great until this weekend. No changes at all since those maintenance items were done. Will start with the usual suspects, clean the MAF wire, clean the IAC, then pull and check plugs. Maybe I'll take a look at the TPS reading, but that shouldn't cause a miss...Any other suggestions?

 

[1wild-horse]

blower motor resistor for the fan problem.
as for the miss, you have any way to look at the data stream? check the fuel trims for a small vac leak. have you drove it much since the symtoms showed up? might not have had enough time to set a light. sounds like your on the right track with the first few things your checking. G/L

 

[Cobra-21]

Thanks for the reply, I priced the resistor at the dealership and it's $56.30 !! I may check at Tousley or RockAuto.

I do have a Predator I can use as a scanner or datalogger. If I look at fuel trims what will I be looking for? Short Term, Long Term ?? How does that relate to vacuum?

 

[1wild-horse]

You will want to look at them both. Warm the car to operating temp. first. Note what the values are at idle, rev the motor above 2000 rpm and watch to see if the values drop. I dont use a preadator to data log so i dont really know what they use so i cant give you any numbers. If it's read in a % they will be above +10% and will return to normal around + or - 5%. but if u know what they are at idle and they drop when you rev the eng. that indicates a vac. leak.