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'84 245 Rough Idle[ALL/1998] posted by Jim Sassman on
Sunday, 13 July 1997, at 6:48 p.m.
I had posted a message regarding this problem about a month ago. At
that time, I used incorrect terminology. I said the engine was miss-
ing. This could be interpredted to mean it was 'misfiring'. Since
two shops have put the engine on an ignition analyzer, we now know
this is not the problem. And it is not, as someone emailed me, the
intake manifold gasket leaking. They checked for leaks in the entire
underhood injection system and found none. All injector o-rings are
good. One thing found was that the engine is running lean.
However, the last mechanic suspects that there is carbon in the intake
valves. He put a cleaner in the fuel tank which did not take care of
the problem. At $ 18 for a bottle, this was an expensive failure....
Now I'm wondering if the engine needs a valve job? There is no
evidence of oil burning or consumption by any combustion process. The
front and rear engine oil seals do leak slightly--but not enough to
leave any evidence on the pavement. (Incidentally, the lower engine
shroud is missing--so oil leaking would definitely show up under the
engine on the pavement.
One further problem: the Lambda Sond dash warning light just came
on today. Is this something that any qualified mechanic can reset
or do I need to take this to an authorized Volvo dealership?
Any help with these questions would be appreciated!
Jim Sassman
'76 245 180,000 mi.
'84 245 159,000 mi
Re: '84 245 Rough Idle[ALL/1998] posted by paul mohney on
Sunday, 13 July 1997, at 9:21 p.m.
Remember to ckekc all your basics, b/4 you hand your cheque book to someone and bendover your fender
there are about a dozen things that can cause rough idle, a leaking injector, a funky sensor. if the lamda-sond is mis reading . or has gone south (have this checked by someone who knows their but fronk
a hot rock,as the inter-relation of the lamda-sond to the rest of the fuel meterinbg system, has got to be understood b/4 you run off into the woods ,taking candy from strangers. ask one odf the pros, here like stoney to exchange, e.mails, and get into a chat where you can exchange info.
Remember check the basics,. hoses,seals wires and sensors
b. looking for you Paul in Santa Ana
Re: '84 245 Rough Idle[ALL/1998] posted by Stoney on
Sunday, 13 July 1997, at 9:54 p.m.
Jim, Sorry to hear you're getting the tango done on you. I'm not really knowledgeable about FI systems, so lets see if Abe or Robert can help.
The only real advice I can give you is 1)Get a belly pan on that sucker ASAP, I've seen more than one steering rack FUBARed by Mother Nature and the DOT 'cause of amising belly pan. I ususally find ''em a a JUNQUE yard for $15-25.
2) Start a diary covering what has been checked out, how it was checked out, what was found, any parts changed, etc. This will save you $ as it will tell the next guy where to start and how much damage has already been done.
Finally, have you had engine computer checked out? My 82 245 had similar symptoms, then went Postal on me and we finally had to do a lobotomy. The new computer cure all the ills. (New unit was from JUNQUE yard and cost $50-I went thru 5 wrecks to find the right one).
Re: '84 245 Rough Idle[ALL/1998] posted by Mark Klein on
Tuesday, 15 July 1997, at 8:47 p.m.
If you know it is running lean, this needs to be addressed before you do anything else. The air mass meter would be fairly easy to condemn/eliminate. The screw on the AMM is the idle mixture adjustment. If you disconnect the O2 sensor, you should be able to set the mixture to get a voltage of about .85 to .90 volts at the disconnected sensor lead (with the engine at operating temp). If the voltage is not near this value, try turning the adjustment screw. It may take a few turns. Give it a couple seconds to respond to your adjustment. If the voltage is very low (below .5 volts) and won't go up regardless of screw setting, the AMM may very well be the problem. If the AMM doesn't respond to adjustments, then it may be the cause of the problem.
The O2 sensor may cause similar symptoms. If it is malfunctioning, when you disconnect it (with the engine at operating temp), the engine may start idling smoother when the sensor lead is disconnected. The F/I control unit is then running in open loop with no modified mixture and running at base settings.