2000 S40 - Low, Erratic Idle

AGSchear · Post by **AGSchear** » 17 Oct 2012, 23:06

My issues with my 2000 S40 continue. I'm not out of the woods just yet!

Last week I replaced the FPR and IAC valve after the car wouldn't start without a foot on the gas pedal. It starts just like new now and has even eliminated my issue of a 8 to 10 second crank time.

However, despite the fix, I immediately got a new CEL code and now, a week later, a very low, rough, jumpy idle tonight. I will pull the code in the morning again, but it had to do with a sensor and high voltage from what I remember. Anyway, the idle sat at about 400 rpm when stopped tonight, both in park and at red lights. If left alone it would periodically move up, step by step, to about 700, and then back down again.

I have been searching for about an hour and figured that tomorrow I'll clean the the throttle body since I haven't yet, and possibly reset the ECU, though I'm unsure if either will help.

Anyone have any bright ideas? I checked all my hoses (or tried to) last week before buying new parts, and didn't notice anything. I can always look more.

Thanks in advance. You guys are great.

Post by **cmblackburn** » 18 Oct 2012, 06:40

Sounds like a dirty ETM, from my experience with 2 newer Volvo's with that problem (high voltage, rough jumpy idle)-One was TPS related, replaced with a contact-less and that cured the problem.
The hard starting could be MAF sensor related, but you say you fixed that.
It's possible to repair the ETM, but a pain in the butt. I believe different ETM's from different Volvo models/years are compatible.

Post by **zulu-v40** » 18 Oct 2012, 12:11

This model has a fly-by-wire throttle. There is no ETM, but the throttle could very well be dirty. It is possible to clean the Throttle Position Sensor too. It's attached to the throttle body and is easy to remove. Erratic idle could be spark plug or coil pack related. Maybe there's a vacuum leak in there too. What was the code?

AGSchear · Post by **AGSchear** » 18 Oct 2012, 18:37

The code it's throwing is P0113 - http://www.obd-codes.com/p0113

It started giving me this code once I installed the new IAC valve and FPR last week to get the car running again. All systems were go then, so I figured it couldn't be too huge of an issue, but one I'd still look into. Unfortunately it has me looking into it sooner than I wanted to.

Idle was down to the 200-300 range when I was driving to the supermarket an hour ago. Stalled when coming to a stop in reverse in the parking lot.

I plan to try and clean the throttle body in the morning. Will report back with results. Now to search for a how-to.

This car doesn't have many more straws for me.

Edit: I noticed doing a search that I cleaned a temperature sensor on the intercooler, and not the MAP sensor, when I was doing my repair last week. I cleaned that sensor with MAF spray...could that be bad? I can't imagine it would cause my stalling problem, but thought I'd add it in there. I'll go ahead and clean the actual MAP sensor, the one under the fuel rail, in the morning too...

AGSchear · Post by **AGSchear** » 19 Oct 2012, 11:12

Cleaned the MAF sensor, MAP sensor, and TB this morning with the according sprays. No luck with the low idle problem. I also checked on the plugs, wires, coils to make sure nothing was loose under there. Checked with my finger over the oil dipstick hole and felt a light suction, so I don't think the PCV is clogged either.

My personal next guess would be to replace the MAP sensor or find a vacuum leak, but I'm totally unsure...
I found a video on Youtube about finding vacuum leaks with carb spray, but he says to make sure you have a fire extinguisher