Intermittent Starting Problem
Thread Starter
3rd Gear
Joined: Jan 2003
Posts: 3
Likes: 0
From: Wixom MI
Intermittent Starting Problem
My 95 with CA Smog does not start occassionally. Yesterday at 11am it would crank and crank, but not start. After multiple tries I had it towed to the Chevy dealer so they could run codes on it.
When I dropped it off at about 1PM the Service Manager tried and got it to almost catch, but it sputtered out and then nothing. At 3:00 or so the Tech got it to start on the first try while bringing it into their bays. They ran the codes on it and all that came up were PO160 and PO161 which are supposedly post cat O2 sensor issues. I have a Corsa exhaust so there isn't an O2 sensor at all.
So far both the dealer and my regular technician have checked the fuel pressure and all of the battery connections. When it does start it runs strong with out any hint of a problem.
Anybody out there have a similiar problem that they were able to solve?
Jocko95
When I dropped it off at about 1PM the Service Manager tried and got it to almost catch, but it sputtered out and then nothing. At 3:00 or so the Tech got it to start on the first try while bringing it into their bays. They ran the codes on it and all that came up were PO160 and PO161 which are supposedly post cat O2 sensor issues. I have a Corsa exhaust so there isn't an O2 sensor at all.
So far both the dealer and my regular technician have checked the fuel pressure and all of the battery connections. When it does start it runs strong with out any hint of a problem.
Anybody out there have a similiar problem that they were able to solve?
Jocko95
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
When it won't start, that is the time to do some testing !!!!
Engines need spark (and at the right time), fuel and air (and in the right ratio) to start and run. Check for spark and timing with a timing light during cranking. Measure fuel pressure at the shraeder valve on the end of the fuel rail. Unplug an injector and put a noid light (available at parts stores), or a low power 12 v lamp like a side marker lamp across the injector socket and see if it pulses when cranking. Unplug the MAF sensor and try to start it. A successful start could mean a defective MAF.
Engines need spark (and at the right time), fuel and air (and in the right ratio) to start and run. Check for spark and timing with a timing light during cranking. Measure fuel pressure at the shraeder valve on the end of the fuel rail. Unplug an injector and put a noid light (available at parts stores), or a low power 12 v lamp like a side marker lamp across the injector socket and see if it pulses when cranking. Unplug the MAF sensor and try to start it. A successful start could mean a defective MAF.
Pro
Joined: Jun 2001
Posts: 509
Likes: 5
From: Edmonds WA
Sounds very similar to an intermittent start problem I had with my 87. Mine would start if I gave it part throttle. It turned out to be the idle control valve/motor. It was sticking shut and wouldn't allow any air into the engine when the throttle butterfly was shut. There were no codes because, as far as the computer is concerned, it's just giving a command to the motor and that's it--the problem is the motor can't obey the command.
I replaced a MAF sensor for hundreds of dollars in the midst of the guessing game, whereas the idle control valve was less than $50, if I recall right.
Best of luck! Intermittent problems can be frustrating!
I replaced a MAF sensor for hundreds of dollars in the midst of the guessing game, whereas the idle control valve was less than $50, if I recall right.
Best of luck! Intermittent problems can be frustrating!
