I've got a 5.9 ltr 1995 Ram 1500 2 wheel drive. Running poorly with check engine light on and some backfiring along with a very rough idle that sounds like it's sucking air. Took it in to a shop. They said they only got a code for the trans temp sensor too hot. But I've gotten codes forO2 sensor voltage too high, as well. They measured a vacuum leak going from 1800 to 900. What would cause this? They admitted they do not know much about the OBDI system and did not charge me for all the testing. Idle air control valve, O2 sensor, Throttle Position Sensor, EGR Valve?

 

Let me clarify. Starts fine runs fine......for a while. Sometimes for minutes sometimes for days. It seems since it has been cooler (in the 50s and 60s) its been running better. Need to take it to a Stealer I guess. They're the Xperts.

 

wow.. i bet they like you !!!

 

What do you mean they measured a vacuum leak from 1800 to 900?

Backfire out the exhaust is rich. Backfire through the tb is lean. Have you changed or cleanedthe air filter lately?
Try bypassing your egr.

 

Backfire through the tb. Sorry they told me that the vacuum was surging the rpms up and down between 900 and 1800 while idling. They said thatit was fluctuating too much. How do I bypass the egr? They were not very forthcoming as to what exact tests they did on it, but said they checked the fuel pressure and it was good. I myself put a new air filter in 2 weeks ago in an attempt to fix. I certainly can throw parts (egr,tps.iac, o2 sensor) at it they are not that costly just my time. But I just want it to work. I've been reading posts and seems several people have experienced this. It seems there are many combinations to fix this. Swap out any of the above parts along with a good tb cleaning.

 

[align=left]Ok. Heres what I found out. Took this thing to a dealer. They said o2 sensor bad and shotty wiring like someone messed with it. Also a weird wiring issue to my pcm like someone cut a wire and then spliced in a short 2" piece of wire. Also in need of tune-up, wires, plugs, cap, rotor, coil and air horn gasket. Paid dealer $400 to fix the wiring and replace the o2 sensor and the new air horn gasket (what a rip off). Drove fine for 3 days. No more sucking sound. Then all the same problems started up again minus the sucking sound. At home replaced the cap, rotor, wires, plugs (non platinum) and coil. Still runs like crap. I actually am at the dealer right now waiting for a diagnosis. At a loss as to what the problem actually is. I would rather not just keep throwing parts at the problem if they are not going to fix it. And seriously don't want to pay a dealer's prices either.Seems like something is sending the wrong signals to the pcm and adjusting the air/fuel/throttle mixture improperly. Don't think it's a vacuum problem.
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Sorry that you are having problems with your 1995.

The return of the problem indicates the dealership got it wrong with their emphasis on the O2 sensor.

Check all around for vacuum leaks, including these two areas that have been mentioned many times by 1994-1995 owners:

1. In the vacuum lines running to the cruise control servo under and near the battery. Look for areas where battery acid fumes could drop onto and ruin vacuum lines.

2. Check all vacuum lines going through the rubber grommet low on the firewall where vacuum and electrical lines enter the pickup cab.

Rough running at idle can be caused by the EGR system.
The EGR system was on the 1992-1995 Ram pickups and then went away for several years so some technicans at dealerships don't have extensive experience with the early versions, but it should have set a code. The EGR on a 1995 Ram has two things you should bear in mind: with years and mileage the pintle valve seat corrodes away letting exhaust gas flow into intake manifold when it should be cut off. This causes rough running. The second thing is that the EGR is required by the EPA/CARB rules to be 'fail safe' meaning that if anything goes wrong with it, the EGR turns ON FULL FLOW rather than turning off like would be someone's first guess. Blocking temporarily the EGR tube that runs from the passenger side exhaust manifold to the back of the intake manifold can help pin-point if it is the problem by eliminating the chance that exhaust gas is getting into the manifold and causing a rough idle & backfiring through the throttle body.

The dealership techs should have checked out your IAC valve and stepper motor to make sure that they are not causing idle problems. That can also be a source of rough idle but seldom backfiring.

With age and high mileage the distributor bushing can get very worn and throw the ignition timing off, as well as the fuel injector sync because an additional sensor for sync is inside the distributor body.

Also make sure that the ignition wires are routed according to this TSB:

http://dodgeram.info/tsb/1998/18-48-98/18-48-98-v8.htm

Wires to cylinder 5 and 7 can easily 'crossfire' one another.

Wires to cylinder 6 and 8 are easily to reverse because they aren't routed the way most would guess.

 

Dealer says all my components are good tps,iac,egr,map sensor, o2 sensor. As well as the wire routing.However they found discrepency between the gauge temp sensor and the temp sensor that goes to the pcm. They said that was the problem. Told them to go ahead and fix this. Nope didn't fix the problem. Now they say it's the pcm that it has an intermittent ground short and needs to be replaced. They say $500 for oem rebuilt or $400 for Carquest rebuilt. Does this sound good? Also I guess there is nothing left to repair after that. Any ideas or suggestions?

 

From what you have told us so far,
it looks like the dealership tech is lost and making guesses.

I have heard of very few 1994-1995 PCM computers going bad,
and what few I have heard about failed when owners installed
aftermarket ignition coils that overloaded the electronic coil current switch
inside the PCM.

It is also rare (but not impossible) for the PCM computer to be working good and then go bad, and then be good again. Usually that indicates an electrical wiring problem to or from the PCM computer, and not the computer itself. Before letting them change out the PCM computer make them promise to refund your money if that does not solve the problem....they should have refunded your money for that new O2 sensor they put on without a cure too!

I know it sounds strange,
but there have been many reports from 1994-1995 Ram owners
that if the battery is beginning to go bad the truck starts acting really strange. Part of this may be due to the voltage regulator being inside the PCM computer instead of being a separate part. Be 100% sure the battery is A-OK by swapping in another battery that is known to be good and then doing some test drives.

In terms of bad wires,
look over all the plugs and bolted connections on the wiring harness
looking for the pale lime colored crud that electricans call 'Green Death'
and clean off any you find to bright shiny copper.

Another common problem on all 1994-2001 Rams is that when the fuel pump submerged in the tank starts to go bad it begins to cut out suddenly, causing the engine to either run extremely rough or just die, then if you shut off the truck with the key and restart it will run ok again for a while until the electrical 'thermal cut out' inside the fuel pump motor gets hot enough to open again. How old is your fuel pump module?

Do you know how to check for 'check engine trouble codes'
yourself by turning the ignition key part way without starting the engine?
You turn the key off-on-off-on-off-on
and leave it in the on position
wait several seconds
then count the 'blinks' of the 'check engine light'
where longer pauses between blinks means start a new number.
Have a paper and pencil on hand to make a mark on the paper
with each engine blink because it is hard to hold them just in your head as a memory. I always have to run through this 3 times to make sure I have counted blinks right.

Bad PCM
Bad EGR
Bad wires
will all be expected to set a unique trouble code number telling you what the problem is.

The fuel pump problem won't set a check engine code.
You can only find this problem by connecting a fuel pump gauge to the fuel injector rail and watching for the psi of the fuel to suddenly drop just before the engine begins misbehaving.

Good luck.

If the dealership does not treat you fairly
ask for an appointment with the
Chrysler Regional Zone representative
and tell him your story.

 

Thanks for the info HankL. I really appreciate it. The only codes I got some time ago were: 24 tps voltage high, 53 pcm failure, 21 o2 sensor shorted, 31 solenoid circuit open/short, 37 trans temp sensor too high. Currently the truck is at the dealer, they are installing a pcm from carquest. We'll see what that brings. I do also know there was an aftermarket remote starter installed when I bought the truck. However the previous owners disconnected it. That may have something to do with the shorting in the pcm. The fuel rail was checked for pressure and I know they said it was good. Once the dealer finally determines what the problem is and it is fixed I will then fight for money back. I think all of the things that were repaired needed to be done but not what was causing the trouble. So I am at the mercy of the dealer now but will eventually prevail.
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