850 threw codes 300 303 304 305 the quit running

rmburns18 · Post by **rmburns18** » 30 Nov 2008, 09:16

I have a 1996 855 non turbo with 200k. it has been running great and on thanksgiving going up a mountain in north carolina cel started flashing and was throwing codes po 300 303 304 and 305. it quit running and now wont start. I replaced the fuel pump relay. And can hear the fuel pump running when the key is turned on. It has bee throwing cod po 172 the last couple of weeks every 100 miles or so.

Any Ideas?

Post by **VCA** » 30 Nov 2008, 11:02

rmburns18 wrote:I have a 1996 855 non turbo with 200k. it has been running great and on thanksgiving going up a mountain in north carolina cel started flashing and was throwing codes po 300 303 304 and 305. it quit running and now wont start. I replaced the fuel pump relay. And can hear the fuel pump running when the key is turned on. It has bee throwing cod po 172 the last couple of weeks every 100 miles or so.

Any Ideas?

Have you checked for spark? The P0300 series codes are misfire codes and P0172 is 'system too rich'. The two taken together sounds like either a) you've got a spark problem or b) your MAF sensor has died. Check for spark at the plug wires, if there is spark, disconnect the MAF sensor and see if it starts and runs. If no spark, check coil and coil wire, then check the distributor if no fault in coil or coil wire is found.

If none of these are diagnostic, post back. Good luck!

rmburns18 · Post by **rmburns18** » 30 Nov 2008, 14:05

Thanks for the reply. Ihave replaced the dist cap and rotor. There is spark and checked fuel at rail valve and have good fuel pressure.

When you turn the key-- engine turns over but acts like no spark or fuel.

Any other ideas?

Post by **VCA** » 30 Nov 2008, 14:16

rmburns18 wrote:Thanks for the reply. Ihave replaced the dist cap and rotor. There is spark and checked fuel at rail valve and have good fuel pressure.

When you turn the key-- engine turns over but acts like no spark or fuel.

Any other ideas?

Did disconnecting the MAF sensor make a difference? Do you have a set of noid lights? (test lights) Check for voltage at injectors when cranking. You might have fuel, but it might not be getting into the engine.

rmburns18 · Post by **rmburns18** » 30 Nov 2008, 15:46

Disconnecting the maf made no difference.

While I'm pretty mechanical-- How do you check the injectors?

Thanks

Post by **VCA** » 30 Nov 2008, 16:06

rmburns18 wrote:Disconnecting the maf made no difference.

While I'm pretty mechanical-- How do you check the injectors?

Thanks

Connect a 12V test light to the harness for one of the injectors (disconnecting the injector)--if the light blinks when the engine is cranked, then the injector has power and is being cycled by the computer.

Taking a step back--are your engine management fuses okay? Take a look in the underhood fuse box and see if any of the fuses are burned out.

rmburns18 · Post by **rmburns18** » 30 Nov 2008, 16:10

Thanks VCA for your assistance. I will check the injectors.
Would the cam sensor cause this problem?

I did check the fuses and all okay

Post by **VCA** » 30 Nov 2008, 17:54

rmburns18 wrote:Thanks VCA for your assistance. I will check the injectors.
Would the cam sensor cause this problem?

I did check the fuses and all okay

Yes, a cam sensor can and will do this...no cam signal = no injector pulse. The Motronic ECU can't use the crank signal (called the RPM signal) for injector pulse timing.

[Warning! Nostalgia ahead!] I had an '88 Buick Park Ave, and lost my cam sensor magnet--much to my surprise, the car gave a trouble code and turned on the Check Engine light but didn't stop running. Turned out the crank balancer was built with two encoder wheels on it--3x and 18x (meaning signals at 3x and 18x per crank revolution), and the ECU would just put the engine in multiport EFI mode instead of sequential EFI and turn on the Check Engine light. Since it was a waste spark ignition system, it didn't effect the spark timing in the least. What a brilliant car...took me 252,000 miles before I bought my Volvo.

rmburns18 · Post by **rmburns18** » 01 Dec 2008, 09:52

Replaced the camshaft sensor and still will not start.

I'm baffled

Post by **VCA** » 01 Dec 2008, 12:10

rmburns18 wrote:Replaced the camshaft sensor and still will not start.

I'm baffled

Then definitely check the injectors for power. I don't think they're cycling.

Guys, what are the normal causes for no injector timing on Motronic 4.3/4.4 systems? I'm more familiar with ME7 and CIS-E systems.