No injector pulse need help

[62bruce]

98 outback 2.5  no injector pulse.  will run with gas splashed into intake until gas used up.

Disconnect cam sensor, no spark. Disconnect crank sensor, no spark.  seems to need both to have spark.

Will not run with or with out MAS plugged in or not.  Does not set a code for MAS when unplugged.

Will set a code for both crank and cam sensors when unplugged... Fuel pump is working fine. hear it prime when key first turned on.

 

My code reader is of limited use. can read and clear, that is about it.

 

Do not know what else to check. I will go out right now and place pressure guage in fuel line, and block return line if I get no pressure reading.

 

I have a cheap set of "noid" lights, it does not flash at all when cranking. There is power to the engine computer, and the hot side of the injectors.

 

I do not know what else to check.

 

Thanks in advance

[Fairtax4me]

The injectors will not pulse if there is an improper signal from either the cam or crank sensors.

 

Was any recent work done to the car like timing belt replacement?

[1 Lucky Texan]

MUST have pulses from crank sensor. Missing 'lugs' on the crank sprocket, bad CPS, ignitor, etc.

 

But, seems like you could have a bad fuel pump or ?

Edited June 14, 2014 by 1 Lucky Texan

[62bruce]

I did the belt, water pump, idlers and tensioner. The heads were machined, and new gaskets. Has been great for about 12,000 miles.  runs fine with gas splashed into intake manifold. Do you think this confirms the belt is correct, or could it still be out ?  I started it one morning and it sat there idling fine. Stopped running a few min later and has not started from there on.  Swapped cam, and crank sensors from another car, no change. Other car runs with these sensors.  other car is a 2000 so no mass airflow sensor to try. I can't think of what else to check.  spark is good, and it will run when primed with gas so I assume the t belt to be correct. I could pull down the front of the engine to check alignment marks ??  I have a second engine computer from a known running car, same same.  all fuses good, 13 volts making it to ECM no problem.  I can manually fire an injector by applying a ground signal at the ECM, and I hear one cyl firing.  for some reason, the ECM will not pulse the injectors.

 

Thanks in advance

[62bruce]

Forgot to say, checked fuel pressure, somewhere around 50 psi,   seems good.

[1 Lucky Texan]

any codes stored?

[Fairtax4me]

With the key On the injectors will have 12V and you should see 12v at each injector ground wire at the ECU. If no or low voltage at the ECU pins, pull apart the three big plugs on the bell-housing and make sure theyre clean inside. No dirt or corrosion.

 

Might want to check timing marks just to be sure. The tensioners on those engines are known to fail and let the belt skip.

[62bruce]

I guess I am looking at pulling down the front of the engine. Good voltage at the ECM, no problem there. The 3 plugs on the right side of the bell housing look like new, and made sure they are snapped together all the way.  I have a pin out for the ECM.

 

The only thing I have no way to check is the MAS.  should it set a code when unplugged ?

 

If the belt was out enough to prevent injector pulse, would the engine still run smooth when primed ?

 

Thanks again

[Fairtax4me]

Hard to say. It'll run in open loop anyway because its cold, and if the injectors were working the mixture would be rich. Timing generally isn't a major factor until the engine gets warm, so running for 3-5 seconds with no load isn't much time to tell if timing is a problem.

 

If MAF is bad the ECU will go into open loop when the MAF is unplugged. Unplugging the MAF would at least allow the engine to start and run if the MAF is the problem, though it won't run very well. Not sure why you don't get a code for it.

 

Do you have solid 12v on all 4 injector wires at the ECU when cranking?

Have you checked for continuity between the injector ground wires?

 

ECU signals ground via the Intake manifold. Either on the lower rear corner on the drivers side, or on top center by the coil. 4 ground wires, all go through the largest plug on the bell-housing.

[john in KY]

I seem to recall something changed with the crank/cam sensors during the mid 90s. Just mentioning this because there is a chance that "known good" 2000 sensor is not compatible with your engine. Something like 4 lobes vs 8 or something like that. 

[62bruce]

Well, more testing.

The 4 ground wires, 2 and 2 crimped together on eye lugs bolted to intake manifold near coil. Good continuity to ECM.

 

Got another car of the same year, etc, to test my MAS, the other car ran perfect with my MAS. Disconnected my MAS and it DID set a code.

Also, the engine did run, but not real well at an Idle with the MAS unplugged.

 

I am running out of ideas to check.  Taking the car in to a shop will exceed the value of the car for the repair bill. 

 

Any help is welcome. Thanks to all for the help.

 

Bruce

[1 Lucky Texan]

what code was set?

 

checked the cam/crank timing yet?

 

also, confirm the big IAC hose is attached to the intake.

[Fairtax4me]

If you unplug one of the injectors and try to crank it, do you get a code for that injector?

[62bruce]

when I tried my MAS on the other running 98 outback, it ran perfect. No code was set untill I un plugged the MAS to see if it would run with out it.

It did run, the idle was poor, but it ran. A code P0102 was set that is "MAS circuit low input "  I plugged it back in, cleared the code and it was fine.

 

I can not explain why my 98 outback does NOT set a code when the MAS is unplugged.

 

I can get a code set by unplugging an injector ( P0201 ) That says to me that the ECM sees the injectors ok.

 

The only thing I have not done yet is to pull down the front of the engine to check belt alignment. I will pull it down after work this week. I noted earlier that the engine runs and idles smoothly when manually primed with some gas in the intake, so I suspect it is good, but until I pull it apart and check, I guess I do not know. 

 

Thanks again for all the replies.