Hi folks... I haven't been here for some time, but I've been searching for an answer for my current problem: As the thread title says, between 30 > 50 MPH, when I lift off the gas peddle, the truck bucks like someone is turning off/on the ignition/fuel flow rapidly. I've replaced: plugs/wires/cap/rotor/coil... I have not done the code check yet, as I just read about that tonight in another thread... (thanks Seal)

Any thoughts on this?

Thanks,
Bonehead

 

Hello again!

I've been busy lately, but had a chance tonight to check
the codes...

Here they are:

11,12,21,37,51

I put Sea Foam in the gas/oil, and the truck runs better... So, I'm
gonna replace fuel pump/filter...

Any other ideas welcomed!

Thanks,
Brian

 

11 Timing belt skipped 1 tooth or more from initial learned value, Intermittent loss of either camshaft or crankshaft position sensor, No crank reference signal detected during engine cranking
12 Direct battery input to PCM was disconnected within the last 50 key-on cycles (normal)
21 02s sensor problem (oxygen sensor), upstream or down stream
37 Torque converter clutch solenoid CKT or park/neutral switch failure
51 Fuel system lean

The code 11 may be the hall effect switch in the distributer and could be the answer to your problem. The code 21 will cause the code 51 so you need to take care of the O2 sensor problem.

 

Thanks Seal!

I was at Auto Zone, and the guy there said it sounded like a bad fuel pump relay...
but I'm gonna go ahead and change the Hall Effect switch and the O2 sensor too.

 

I doubt it is the relay. That relay usually works or it doesn't.

 

I was getting the 11 and 51 codes and replaced that sensor, and so far so good, has only been a few days though. That thing was a pain in the !@# though.

 

The Hall effect sensor looks real tough to replace... any tricks... besides pulling the distributor?

 

Just so to be sure we're talking about the same thing, the sensor I replaced was just underneath the distributor cap in the in the distributor. My Haynes manual called it a 'camshaft position sensor', and the auto parts store called it a distributor something or other.

Anyway, I don't know what's all involved in pulling the distributor (kind of a newbie to this stuff), but in the long run it may prove easier. There were 2 screws on the distributor I had to unscrew, one in the front and one in the back. The one in the back barely had enough clearance to get my fingers back there, so I had to use one of those right angle ratcheting wrenches with a screw driver head on it to get both screws out. That was difficult, but the harder part was once the new sensor was in, aligning the screw holes on the sensor with those on the distributor to be able to screw the screws back in, holy hell what a pain in the ***. You can't see anything so it all has to be done by feel. I used a drill bit to verify the screw holes in the front were lined up, but couldn't really do anything with the back. So that would be much easier if you pulled the distributor completely out.

 

Names; In 1974-87 pick-up coils were used, 88-91 the Hall Effect switch was used, and 92-93 camshaft position sensors were used. All of these served the same function and activated the same codes when they failed. In the Chrysler parts departments the camshaft position sensor was called the switch plate assembly when they first came out. Those little screws are a pain but I changed mine in the truck.

 

Thanks for all the info guys....

That screw on the back-side of the distributor is gonna be a bear, but......
I'm thinking of taking the truck to a collision shop in town that does Labor...
by the hour, for installing customer supplied parts.

Any one want to guess how much time I should expect to do the job?

Thanks,
Brian