95 960 cleared check eng code, now it surges at idle, no pwr

Tim Peterson · Post by **Tim Peterson** » 17 Feb 2009, 09:38

Hello,
I have a 1995 Volvo 960 with 127,000 miles. It has the straight 6 dohc engine. All regular maintenance has been done. Recently, I lost the gas cap and before I could replace it the check engine light came on. No sign of any other problems. I cleared the check engine code by using the obdI control module, using the "A2" module to clear the code by pushing the button and reading the red LED light sequence per instructions I found at Bay 13. After clearing the code, the engine now surges from 1,100 to almost a dead stop during idle. Once moving, the car has little power. It hesitates badly upon acceleration and often stalls when slowed down for a stop sign or turn. I'm completely paranoid that somehow I've fried the ECU. Is there any way to tell if the ECU is fried? What other problems might be causing these symptoms?

Post by **billofdurham** » 17 Feb 2009, 11:49

Welcome to Matthew's Volvo Site.

Which codes did you have recorded and have you checked the OBD again to see if any have returned?

Bill.

Tim Peterson · Post by **Tim Peterson** » 18 Feb 2009, 15:55

I can't remember the original code sequence before I cleared the memory, but I do remember that the codes indicated an emissions error per a chart I found online. I've since checked the OBD A2 module again, now no codes come up, it just gives a flash, pause, flash, pause, flash, which I believe means there are no stored codes. My intuition tells me to suspect that there might be a problem completely unrelated to the ECU. I have a hunch that an ignition coil might have gone bad. Do the symptoms fit that sort of malfunction? I had similar symptoms from a 2002 VW Passat that had defective ignition coils. What do you think?

Post by **billofdurham** » 19 Feb 2009, 12:35

What you describe is code 1-1-1 which is no fault codes stored.

There is a possibilty that one or more of the coils is going bad, but which?

By the way I don't think you need to worry about "frying the ECU" by reading codes. This is a normal thing to do.

Bill.

Tim Peterson · Post by **Tim Peterson** » 20 Feb 2009, 15:16

So, I took this beast into a shop to have it checked out for a bad coil. I also thought maybe there is some sort of vacuum leak, so I had them check for that too. The coils are fine, and no vacuum leaks were found, however, the Mass Air Flow box and the Idle air control module were full of gooey white stuff which he says is coming from the PVC system They cleaned both out and the car now idles okay but there is still no power. They suspect engine wear or a clogged catalytic converter is the source of the power loss. That doesn't make sense to me since the power loss was dramatic, all at once, not at all gradual. It should be noted that the mechanic that performed the work mentioned above is not a Volvo expert and seems somewhat baffled by the pre-1996 OBD system. He made it sound like the only way to determine the cause was to start replacing parts. Yikes, that could get very expensive in a hurry. Any help you can give will be a huge favor.

DanR · Post by **DanR** » 20 Feb 2009, 17:39

You should have them check the fuel pressure. That has caused the symptoms you describe on my car. It was a bad fuel pump. Seems it was just pumping enough to idle the engine, but any acceleration caused it sputter and sometimes die.

As to the gooey white stuff, when the car is run, is it for just short trips? If not, could your coolant sensor and t-stat be bad at the same time? Is there heat?

Not sure about the '95 but on the "94 there are two coolant sensors, one for the gauge on dash board and the other for the ecm.

Bad throttle sensor, bad MAF (air mass sensor), the MAF is easy to diagnose, with the engine off, disconnect the sensor, and start the engine, if it runs better, try cleaning it, but most likely it is fried and will need to be replaced.

DanR '94 964 342,000 miles (108,000 on the new engine)