viperrt96
Enthusiast
I've been having this drivability problem that I've been working on now for a few weeks. Looks like I got to turn to the professionals. If not here I'll have to take it to a mechanic for the first time in 5 years of ownership.
First thing First
The only codes I get are:
P-1391 Manufacture specific (manual says intermittent loss of Crank or Cam position) less than .5 volts
P-0108 Map/Baro High input signal
I think the 108 I get because the engine dies while under acceleration and the MAP voltage goes up when the vacuum drops.
Here is the drivability problem.
When the code is cleared and I drive the car easy. It runs Ok and no problems.
If at anytime I Blip the throttle (quick acceleration ant at RPM's above 5000) the engine cuts off (tach signal goes to zero) and then engine comes back on. It's like turning off and on the motor. Car bucks of course and check engine light comes on
OK
Now this first happened on a Dyno Run I did a few weeks back. It had a quick blip @ 5200 and it was for only a quick second (reflected on the pull). The Dyno operator asked What was that? I dunno? Never done that before. He hooked up his Snap on OBDII reader and recorded. We did three more pulls. It never did it again. No problem found? He said well whatever it is I'm sure it will raise its ugly head.
Well it did. I went to the dragstrip two days later and on my 4th pass it did that exact same thing but for only a quick second. No check engine light yet. The very next run (5th pass) and under quick acceleration (of course) it was magnified. Tach went to Zero,car bucked engine back on and Check engine light on. I was able to drive it home. I just had to baby it.
I checked the manual and noticed the Crank,Cam,TPS and Map sensor are all tied together. I decided just to replace all four sensors new. I still have the same problem. I know I set the air gap correctly for the cam sensor. I have another stock ECM and it does the same thing with that one. So it's not the ECM. I'm thinking I got a short? Do I get a lab scope and monitor Crank and cam signal pattern? I don't know. I have a good mechanic friend and he says that when he sees that kind of code it's a bad timing chain? I just put a new one on it this winter when I went thru the motor. It ran fine then. The condition I have seems to have come on slow. It's now here to stay. Any Ideas or suggestions?
First thing First
The only codes I get are:
P-1391 Manufacture specific (manual says intermittent loss of Crank or Cam position) less than .5 volts
P-0108 Map/Baro High input signal
I think the 108 I get because the engine dies while under acceleration and the MAP voltage goes up when the vacuum drops.
Here is the drivability problem.
When the code is cleared and I drive the car easy. It runs Ok and no problems.
If at anytime I Blip the throttle (quick acceleration ant at RPM's above 5000) the engine cuts off (tach signal goes to zero) and then engine comes back on. It's like turning off and on the motor. Car bucks of course and check engine light comes on
OK
Now this first happened on a Dyno Run I did a few weeks back. It had a quick blip @ 5200 and it was for only a quick second (reflected on the pull). The Dyno operator asked What was that? I dunno? Never done that before. He hooked up his Snap on OBDII reader and recorded. We did three more pulls. It never did it again. No problem found? He said well whatever it is I'm sure it will raise its ugly head.
Well it did. I went to the dragstrip two days later and on my 4th pass it did that exact same thing but for only a quick second. No check engine light yet. The very next run (5th pass) and under quick acceleration (of course) it was magnified. Tach went to Zero,car bucked engine back on and Check engine light on. I was able to drive it home. I just had to baby it.
I checked the manual and noticed the Crank,Cam,TPS and Map sensor are all tied together. I decided just to replace all four sensors new. I still have the same problem. I know I set the air gap correctly for the cam sensor. I have another stock ECM and it does the same thing with that one. So it's not the ECM. I'm thinking I got a short? Do I get a lab scope and monitor Crank and cam signal pattern? I don't know. I have a good mechanic friend and he says that when he sees that kind of code it's a bad timing chain? I just put a new one on it this winter when I went thru the motor. It ran fine then. The condition I have seems to have come on slow. It's now here to stay. Any Ideas or suggestions?
Good Luck!
