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I just picked me up a 1997 Dodge Ram 1500 4wd with a 360 in it. Truck ran great when I bought it saturday. I knew it needed a tune up and a new charcoal canister and tps sensor. I did the tune up ( plugs, wires, cap, rotor, and pcv valve) replaced the canister and purge valve ( the insides of the canister disenegrated and got all inside the lines so I had to empty the lines and replace the valve and canister) and threw on a new tps. Now, the truck will start, but will not stay running unless I have my foot on the throttle. If I try to let it idle, it will die. Idk if this is a coincidence or something I did. I can’t imagine it is. I’ve checked all my work over and over and everything is correct. When I’m reving it, it definitely stinks of fuel like it’s running rich. I have a pending code but it’s not stored yet and a p1391. Cam and crank signal interfernce. But I know the crank works, the scan tool is picking up the rpm reading. But I don’t see it being the pick up coil because I’m getting spark. It will run. I’m lost. I’m gonna take the throttle body off tomorrow and clean it and the idle air control motor. But does anybody else have any ideas?
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The crank sensor can keep it from starting, but if it has an internal crack, it may work for a bit then stop sending the signal. Also check all the wires and connections for the crank sensor. If I remember correctly, dodge trucks of that era have no egr valve. I mention that because a clogged or malfunctioning egr can cause some of that too.
Yeah I see no egr valve. I can take the crank out though and look at it. Make sure it has no cracks in it. I don’t wanna replace it if I don’t need to. I cleaned the throttle body and the IAC out just now. Made no difference. It’s still doing the same thing.
Keep in mind that the crank sensor is a magnet with a lot of small copper windings encased in plastic and filled with epoxy. I say this because there can be an internal crack not visible to the naked eye. Most sensors and ignition coils are made in a similar fashion. If the crank sensor is expensive locally, check out the online prices from places like rockauto, amazon and eBay.
Replaced the crank, nothing changed. It seems to be running lean with my fuel trim at 30%. That’s only short term though. I cant keep it started long enough to read long term. I decided to see if an injector may be leaking. Nothing. While those were out I decided hey, might as well replace the intake gaskets because I know those plenum pan gaskets go bad and there was oil in my plenum. Just got done. Still nothing changed. It backfires if I Rev it long enough. It will only start with my foot on the throttle. Idle air control I know is good. The old one good but I even replaced it just because it was a cheap part and I already had the old one out. I can’t figure it out. All I did to the truck was a tune up. And now all of this happening. I don’t know if this is coincidence or what. But I seriously am out of ideas.
You mentioned replacing the TPS. If it’s not adjusted properly the computer will not see closed throttle and tell the engine to idle. You might want to check the scan tool data to see if the TPS voltage is close to .5 closed throttle. If not, that could be the issue.
Good luck and keep us posted.
The only thing I can see on the scan tool regarding the tps is just the tps %. Closed throttle I’m still getting 11%. If I unplug it it goes to 100%. If I floor it and go wide open my highest reading is 70%. I even opened the throttle manually under the hood and looked at my reading and it’s still 70%. I can’t get it to 100%. That I’m not sure is normal. But why would the truck backfire?
Did you move the Dist.when replacing the cap/rotor? If you did the Cam/ Crankshaft sensor sync.is not to factory specs…. The cam sensor needs to be within 10 degrees of crank to be in sync…. otherwise the cam signal isn’t recognized by the PCM.
Man, I’m sorry the crank sensor idea was a dud. I had high hopes of that fixing this.
Ok, new train of thought. You said it backfires, and all you did was a tune up. That has to be the source. I had a haynea manual for an altima I used to own. The firing order listed in the picture for my engine was listed exactly backwards. What I mean, is that I did just plugs cap rotor cap and wires, and it kept stalling and backfiring. After many hours, I looked up the firing order online e, and found that the Haynes book I had was a misprint. It purred like a kitten after that. I’m assuming now that the firing order is somehow just off. Recheck your firing order from alternate sources, see if it’s something that simple. I hope it is.I took this video for a friend of mine. It still is hard to tell. But I figured it’s something I can show you guys. I’ll check the firing order later. I’ve looked it over plenty of times because it’s stamped right on the plenum. But I’ll check once again later just to be safe.
Have you checked fuel rail pressure…it started, but then acted like it wasn’t getting fuel when the starter ground away on the video?
When is the last time you changed your fuel filter?
Autopart store wants 150 to rent the tester.. I don’t have enough to rent it yet so I haven’t got to check. And the fuel filter is apart or the pump I assume because the lister for the filter shows non serviceable. So it might be in the tank. I’m not sure. I assumed the pressure was OK though if I can keep reving it and it’ll stay started. Everyone it died it was because my foot wasn’t on the throttle
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