Hi there,

Car is a 1995 Volvo 940, non-turbo with a bosch ignition. At the moment I have a rough idle the whole car is vibrating, the worse it gets the car tries to compensate and raises the idle now it is just above 1100rpm.

Parts already replaced

-plugs, wires, distributor cap, rotor and seals. compression is 180 psi across all 4 cyl.

The check engine code I'm getting is side B, socket 2, and the code is 1-2-2. I've looked through the volvo trouble codes websites however i can't find anything for that specific code.

The other thing is I can't clear the codes, I followed these (240 2.3L ? 740 2.3L/Turbo ? 940 2.3L Turbo (1992 -1995) ? OBD/OBD2 Trouble Codes) instructions however it just won't clear them.

Any help would be appreciated.

 

Are you sure it's a Bosch system? That's a Regina code: https://www.volvoclub.org.uk/faq/EngineOBDCodes.html
It means no signal from the air temp sensor in the air box. To erase codes first write down your security code for the radio,if it's original, and then disconnect the battery for 5 or 10 minutes.

 

Hi,

Yes it is bosch the ignition coil is a cylinder and it says bosch on it. I just did the battery disconnect, codes went away however rough idle still persists it is almost making the car shut off at this point. I cleaned the maf, checked all vacuum hoses, running out of ideas here...

* also new fuel pressure regulator
* even with the terrible idle the fuel economy remains the same

 

the B block doesn't have engine codes on it, it has like airbag and power seat memory diagnostics. the A block pin 2 and pin 6 have the engine codes.

 

any air leaks between the MAF and the cylinder head will cause all sorts of idle and low speed running issues. this includes the seals around the fuel injectors, the little rubber hoses that connect the idle air control valve, etc. warmed up engine, all accessories and a/c switched off, unplug the idle air control, and it should idle at about 600 rpm, plug in the IAC and it should idle at 700 rpm.

 

I've heard of 940's with bosch ignition but regina injection. funky hybrids, for sure. regina injection would have no MAF, it would instead have an air intake temperature sensor where the MAF normally is, and it would have an MAP manifold air pressure thingie over by the brake master cylinder.

 

If it is a Bosch system then you probably have it in the wrong socket and are getting the "cruise control not functioning code"

With Ignition & Cruise Selector "On"
Code Fault Check: 1-1-1 No faults detected; speed has exceeded minimum 35 km/h needed for test; i.e., you tested after the car had been driven. No fault
1-1-2 Abnormal speed signal Possible static in speed signal to control 1-2-2 No speed signal, or has not exceeded minimum 35 km/h. This code means the signal from the speed sensor has not been received. It's usually not a failure yet since the system erases the codes every time the ignition is turned off and when you turn it back on the initial status is no signal from the speed sensor since that only comes once the speed exceeds 22 MPH. If you leave the diagnostic connected and go for a ride and then perform this test BEFORE you shut down the ignition the code should come back 1-1-1. If it does not then this code table should be used to identify the issue.
When I first got my car I kept getting this code and thought something was wrong but there wasn't. I would definitely check for vacuum leaks and the idle control valve. Also, re-adjust the throttle position switch, if the computer doesn't know it's in idle then everything will be off. Do steps 3 and 4 to test your sensors and injectors.
https://www.volvoclub.org.uk/faq/EngineOBDCodes.html
My Regina 740 had a rough idle and shaking until I figured out the vacuum pressure sensor wasn't holding vacuum. What kind of mileage are you getting?

 

Ok so, i disconnected the battery overnight cleared all the codes, drove around for a while and finally got the right codes showing now.

They are: 1-2-1 and 2-3-2 on the A side pin 2.

1-2-1 - Mass air flow (MAF) sensor
2-3-2 - Fuel trim (FT), idling – weak/rich

This is more like it, its exactly whats happening with my car. Now to hunt down a MAF because the new one is $500... Thanks for your help , I will post back with the results.

 

before replacing the MAF, I'd check the condition of the rubber elbows that connect the idle air control valve. on a car this old, they are often cracked, and even a pinhole air leak will throw the idle mixture way off.

 

there are some great troubleshooting steps you can take for the MAF that I posted in a different article. Pretty easy to test if you have a multimeter

 

Well I should have done that before I ordered the new MAF.

I replaced the MAF and the problem still persists. At this point I'm out of ideas. Any help would be appreciated. Also the codes are still there.

 

Have you tested the O2 sensor?

https://www.volvoclub.org.uk/faq/Eng...andDiagnostics

 

Unfortunately yes, its in working order.

 

back to intake/vacuum and/or exhaust manifold leaks being a prime candidate.

 

If you have a cigar try this:

https://www.youtube.com/watch?v=zMok2y05jNE

 

Update, took out the oil separator box/flame trap cleaned it out, also checked all vacuum hoses. All is in working order. I also threw in 2 bottles of heet into the gas tank to see if there is any water in there because at this point I don't know what else to check.

BTW This car is driving me nuts right now.

 

Found the culprit, intake manifold gasket. I feel so stupid can't believe I overlooked that. One side of the gasket was disintegrated. Thanks for all your help and suggestions.

 

Glad you found it. That's why pumping smoke into the system works so well. It would have found that immediately. There's a lot of easy, homemade smoke machines on Youtube. A lot of people, including myself, look at the hoses, see they're ok and assume there's no leaks. I had a Ford that was losing coolant and I replaced all the hoses and still couldn't find the leak until I pressurized it and found that it was the factory clamp on one of the hoses that wasn't clamping enough. Replaced it with a worm clamp and the problem was solved.