1993 Dodge Dakota Drivability problems

FORESTGUY57

MEMBER
1993 DODGE DAKOTA

Engine Performance problem
1993 Dodge Dakota V8 Two Wheel Drive Automatic 160k miles

My 1993 Dodge Dakota, 5.2L-V8, Auto Trans, has had 2 head gasket replacement jobs, with the drivability problems starting after 1st head gasket job.

Driving at 65MPH on interstate, engine backfires, then sags, dies. Pull to side of road, after sitting for a few minutes, I can get it started but it will not rev up without bucking, backfiring.

No trouble codes stored in PCM.

I have since replaced: PCM, O2 sensor, Crankshaft sensor, Cam sensor, Coolant temp sensor, intake manifold temp sensor, distributor cap, rotor, plugs, plug wires, Cat. Convertor, muffler. ( Catalytic conv. Had blown all interior components/catalyst into muffler, causing the muffler to clog, raising back-pressure.

Typically, the engine will start fine when cold, upon driving as engine warms up, roughness begins and e=increases to the point that it stalls and backfires, if accelerator is pressed passed certain point, engine sags dramatically, to the point of dieing, back off, it will run again but has no power.

I have gone to each connector, cleaned and checked for snugness, applying dielectric grease to connector upon reinstallation.

The latest is test of distributor gear lash after suggestion from Dodge tech. Pulled distributor, no gear on shaft, still in engine with oil pump shaft attached. I've tried to pull gear out, bit stops after pulling up approx 5 inches with a solid sound of metal stopping it from proceeding. The gear when in contact with camshaft drive gear has approx 1/8 - 3/16 movement. The shaft has no side play however, bushing seems to be in good shape.

An older 318 (5.2L) engine from '66 had distributor gear attached to distributor shaft, this was a surprise when I removed distributor and no gear attached.

I'd appreciate any suggestions on proceeding from here to remove distributor drive hear as well as diagnosing the drivability issue. This problem has been onging since Set. 2008. I am disabled and trying to do this on as little money as possible due to limited income however, I have spent over $1900.00 now on parts. I am not one to throw parts at a problem however after having a repair done at a Tunex franchise, $430.00 later after replacing the cam sensor it ran for about 20 miles before reverting back to the same problem. The Tunex wanted to do a $225.00 engine flush which I refused, as cleaning out the fuel system was easily done myself and the fuel injectors had been recently R&R'd when doing the head gasket job.

Thanks for the help!

Whit

7 Replies

JACOBANDNICKOLAS

MECHANIC
109,650 POSTS

Have you checked the fuel pressure? Also, have you checked the knock sensor? Is will adjust timing so the vehicle runs it's best. Maybe it's going.

Finally, I had a 92 with a similar problem. I had to run the truck with OBD scanner plugged in to find a map sensor was loosing voltage, causing back firing, then the engine would die. Maybe you could consider trying that.

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Friday, January 16th, 2009 AT 12:01 PM

FORESTGUY57

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6 POSTS

Thank you for the response Jac.

I have not checked fuel pressure but will attempt to get a pressure gauge to connect to fuel rail. In looking in the Chilton Manual I have for this dak, it says the 92-93 have a fuel pressure regulated to 14.7 P.S.I. I have an old fashioned Vacuum gauge with fuel pressure capabilities however no connector to attach to the test port on the fuel rail. I'll be making up a gauge and adapter from parts I have here. Unfortunately, I have very limited funds at this point, I've been disabled for a number of years and the fixed income has it's limitations.

I can find no knock sensor on this vehicle, would the 5.2L (318 CID) engine have this sensor on the 1992-93 year models? This truck is a CA. Emissions type and has a combination of 92 and 93 parts installed.

You mentioned the OBD scanner attached to your '92 vehicle.I have been told the OBD scanners will not report anything from this PCM. Is there a particular scanner that will work?

I have tested the sensors statically using DVOM and multimeters but have no analog to test the cam sensor.

In my search for answers, I have seen quite a bit written about the sensitivity of the digital sensors and their effect on the operation of the vehicle.

The initial failing was a sudden backfire then died. I have not found a part that has been bad however the first shop that did a repair changed out the cam sensor and said they also "adjusted the distributor". The truck ran about 20 miles before starting the same problems and now have replaced almost all sensors except for the distance sensor. I'm going to test that today.

Thanks for your help

Whit

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Saturday, January 17th, 2009 AT 9:42 AM

JACOBANDNICKOLAS

MECHANIC
109,650 POSTS

Hi:
I'm at the outher end of the country, but I would still think that it would have a knock sensor. The sensor is responsible for adjusting ignition timing to the perfect advance before the engine starts to ping. I've seen them cause a similar problem. Also, when you had the distributor out, were there any problems noticed with the pick up coil? I'm starting to think it's the distributor itself. You don't know anyone that would allow you to try a new one to see if it fixes the problem?

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Sunday, January 18th, 2009 AT 6:37 PM

FORESTGUY57

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6 POSTS

Hello,

I have searched all over the engine for a knock sensor on this 92/93 Dakota with 5.2L, can't find one anywhere.

As for pickup coil, it's attached solidly with the rivets holding the piece securely in distributor and the cam sensor pickup has been replaced.

The most recent quirk has been the engine stopped running, now will not start at all. I've reindexed the distributor per instructions found on Allpar site, new rotor, cap and plugs. After cranking for a bit, take plugs out, they're wet with fuel.

Got good spark off coil wire but weak off plug wire(s).

This thing seems to develop new problems on a regular basis. Thanks for your help, I appreciate all your suggestions!

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Monday, January 19th, 2009 AT 7:53 PM

JACOBANDNICKOLAS

MECHANIC
109,650 POSTS

Hi:
I am very sorry, but I tried to get a location for the knock sensor but every thing I find says the 5.2 doesn't have one. I must be wrong and I truly apologize for the lost time. I discussed your problem with another mechanic and he said the same thing, the distributor. Can you get one to try?

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Monday, January 19th, 2009 AT 8:12 PM

FORESTGUY57

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That's no problem at all re: the knock sensor. I appreciate all your suggestions and it was good to try to locate the sensor if indeed it did have one.

I've now reinstalled the distributor, and reindexed as per procedure outlined on another website. Attempted to start the truck but unsuccessful. One short "rev then just cranking.

Pulled plug wire, no spark off wire, great spark off coil wire. New rotor and distrib cap, but checked and changed to new again. Plugs are wet with fuel. Voltage dropping to 10.5 volts on cranking.

I've been charging the battery ( which is a new battery, exceeding OEM specs) but still no go.

If I could afford it, I would take all the sensors off, dump the pcm and go back to old style HEI with distrib. And carb.

I'm going to probe all the sensors again to verify they are working and within specs. This problem has been ongoing since Sept, 2008. Have no vehicle to drive and being on a limited income due to disability, do not have unlimited funds to drop on parts. I've already dropped close to $2000. 00 on this truck, money in which I could have put on old style carb and HEI.

Thanks again for youe help and suggestions.

Whit

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Wednesday, January 21st, 2009 AT 12:00 PM

FORESTGUY57

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Hello Folks,

The continuing saga in trying to get my Dak to run.

I found a bad splice on the Black/light blue computer ground wire assembly. This bad ground was not in the place mentioned on many boards but in the wiring harness snaking around the intake manifold. After splicing in new wires, the ruck ran great, almost as good as new. However it set codes 21, 24 and 11. These are the O2 sensor circuit, TPS circuit and no crank reference signal.

After checking these circuits out, I have replaced the O2 sensor with a new one I had purchased before.

Now, I cannot start the engine and in checking, have found the Auto Shutdown relay is not being activated. In looking through my Chilton manual for this truck, the wiring schematic is lacking pinouts on 12 connections on the PCM. I am attempting to trace down the wires but a complete wiring schematic would be helpful. Does anyone have access to a wiring schematic that would cover a 1992-1993 Dakota? The schematic in the Chilton book shows a 1993 schematic that has 2 O2 sensors however my truck has only 1 O2 sensor which corresponds to the 1992.

Any help you may be able to offer on the Auto Shutdown circuit would sure be helpful also. The coil has 12V positive on both connections. I'm assuming the computer is not pulling to ground on on side that should be ground according to the schematic, however I have no idea what the logic is in the computer and what circuits control that ASR circuit.

I'm getting close, last weekend, in a test drive after repairing the ground splice, the truck ran almsot as good as normal.

Thanks in advance for any help offered. You have been very helpful already and I appreciate it.

Whit

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Thursday, January 29th, 2009 AT 9:41 AM