Thank you for getting back to me so promptly. greatly appreciated. here is the problem- the check engine light has come on twice and turned off by itself. the truck is starting to behave as though ( it has bad gas or fuel filter is clogged or o2 sensor is not functon correctly) in traffic at a light she wanted to stall out on me - to keep it going i power braked ( this is the first time I've had to do this with this truck) any suggestions thank you theresa
What makes an 84 dodge truck shut off after running for 15 minutes
Thank you for the information. your very well informed. However since the last time I spoke to you the truck has been running fine up until last week. I still think it is an oxygen/fuel sensor of some kind. This would also cause poor performance in this truck such as bad fuel consumption, lack of power.The trucks service engine light came on today first thing this morning and the truck was running funny. - shut the truck off once I got to my project site - turned it back on later and no more idot light and the truck was running okay as well. Checked the check engine code it flashed 12 twice than flashed 42 any idea what code 42 is? As far as the oil leak, the oil pan gasket needs replacing. Please help. Thank you. Theresa
The problem I see is that your engine is consuming oil and not maintaining pressure. It sounds like the engine is losing compression, possibly through a head gasket problem. Check the coolant - do you see any oil in there? Also, after you drive it for awhile and return home, park it with clean cardboard under the engine on the ground, so that if it's leaking oil, you'll see it and also have a relative idea of where on the engine it's coming out. Since you say there are no leaks though, the oil has to be going somewhere, and the only other places to go would be into the coolant or into the cylinders.
If the engine is losing compression through a tear in the gasket, your transmission may shift more often, especially downshifting when you try to accelerate while already moving - the truck will sense that you're not making the power that you need to accelerate, so it'll drop a gear to try and get the revs up and make the power you're asking for.
With the recent work on the truck (intake manifold gasket) it's possible that it wasn't installed correctly and has a leak. A vacuum leak would definitely cost you power, and the transmission would also shift more as the leak will mislead the computer with what is going on in the engine. Check as well as possible to make sure the gasket is installed smoothly with no folds or tears. Also, look carefully around the area of the manifold and make sure that all hoses and sensors in the area are plugged in. If they had to be undone to change the gasket, there's a chance they weren't reinstalled correctly.
For about $25 you can buy a compression tester and check each cylinder yourself (it's very easy to do). This would tell you right away if the rings are good and the engine is sealing up. You can also have a leakdown test done at a garage, which will tell you whether the valves are seating and sealing properly. Discrepancies between cylinders on either test should be small for example, on a compression test, there's a range of compression numbers that are acceptable (I don't know them for your truck, but go to Barnes and Noble or a parts store, grab a repair manual for your truck, and check the specs). All cylinders must fall within that range, with no more than a certain percentage deviation between the lowest and highest compression. If one of them is drastically different than the others, that's your problem cylinder.
Another idea that you could try, especially since you have idle problems, is to clean the idle air control valve. I don't know exactly where it is on your truck, but a google search for "idle air valve" or "idle speed motor" along with the year, make, and engine in your truck will probably reveal its location. It'll have a couple vacuum lines going to it. You can pull one off, tuck a WD40 spray straw into the hose, and reinstall the hose with the straw sticking out. Make sure it's done so that the straw sprays into the idle valve. With the truck running, spray either some WD40 in there, or some carburetor or air intake cleaner in there, and allow it to clean the idle valve. Sometimes rough idling is a result of carbon buildup that keeps the idle valve from idling the truck well.
You can use the same stuff on your throttle body (find the airbox, and follow the large pipe from it to the throttle body, which is mounted at the end of the intake manifold). Take off the tube that attaches to the throttle body, prop the throttle body open, and spray intake cleaner in there - give it a shot of cleaner, and then scrub it out with an old toothbrush and paper towels. Do it as much as you need to until the throttle body is clean. It helps to have the truck jacked up so that the opening of the throttle body is pointing downward, so that any excess cleaner runs out of the throttle body. Any that goes into the engine is fine - it's meant to be burned off and won't hurt anything.
A final cleaning measure would be to buy some Seafoam at the parts store and clean your intake manifold with it. With the truck running, pull a vacuum line off the manifold and feel for suction. Where you feel the suction is where you'll put the Seafoam in. Stop the truck, and use some PVC line (aka fishtank tubing) - stick it into the nipple on the manifold, tape up around it, and start the truck. Pour about a half a coffee cup of Seafoam and put the other end of the hose into it. The truck will **** it up quickly. You may want someone in the driver's seat to hold the RPM around 2000, so that the truck doesn't stall - this is only necessary for a couple minutes until the idle stabilizes. It'll run rough for a few minutes and will have smoke billowing out of the tailpipes - this is excess carbon residue being burned off. Let it run for 10-15 minutes like this and it should be enough to burn off the majority of the smoke. There may be a little bit left that you see next time you drive, but it's harmless and will go away quickly. Seafoam is great - it makes a huge difference in the way the truck will run, idle, and drive, and at less than $8 per can, it's cheap to use.
As for the issues with shifting, get some electrical contact cleaner at Radio Shack and spray every electrical connection you find underhood. Let it dry for about 10 minutes, then plug it back in. You may have some corrosion on the connector terminals, and that can screw up the readings and cause the computer to receive false information. No guarantee on that fixing it, but it's a good start and good preventative maintenance anyhow.
Try this stuff out and let me know how it goes - I'll be able to reply again more quickly next time, I promise:)
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a couple other things have been happening since the check engine light has come on - the trans is trying to shift more than normally and im burning more oil than normal and my oil pressure gauge is not up where it should be- not sure why - have done a lot of work to this truck - the motor is strong - the trans has been good - she has 257,000 miles on her and is in pretty good shape - the intake manifold gasket has been replaced - I have a strong feeling its a sensor of some kind - there are no leaks of any kind
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