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My truck’s plenum gasket is fixed and the misfires are gone, but it still has a hesitation between 2000 and 2500 rpm. The engine tone deepens and it just won’t rev any higher. If you give it a bit more throttle, it’ll kick down and take off whereas before it would fall flat on its face, so that’s good. But I still don’t understand why this hesitation is there. The truck had, more than likely, over 5,000 miles put on it where it was burning enough oil to misfire. Is it possible my cat is plugged? Or do I just need to give it some time to burn the carbon out of the cylinders?
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You could cause excessive wear on the cylinders with the misfire. How excessive will depend on who you speak with… (Burned valves – Warped heads so on)
The most common thing you will hear – The exhaust catalyst will be damaged by the unburned fuel being poured into it. Best case, the converter breaks apart, worst case it clogs. Both cases require replacement at $500-1000.Chances are if your plenum gasket has failed there are other gaskets (Vacuum line) That need to be addressed.
Your issue sounds like a lean fuel condition or a fuel atomization issue…
Things to check.
Fuel pressure.
Fuel filter.
Fuel Pressure Regulator.
Tps. (throttle position sensor)
Timing.(Vacuum advance)
Basic tune up.
How many miles?Time for a overhaul???
Check Codes- Pre 96 OBD1 You will need to preform (KOER-KOEO){KEY ON ENGINE RUNNING}{KEY ON ENGINE OFF}TEST.
After 96 OBD2 You take have codes checked at autozone.There are even some items on the transmission of some cars and trucks that can cause issues like this…
Could the engine be throwing its self into limp mode???This really sounds like a lack of fuel or fuel being cut off.
Are you getting any smoke out of the tail pipe???Black = To much fuel.
Im sorry I missed you original post on this issue…
Can you give me any more info… MAKE – MODEL – YEAR – ENGINE -MILES.1999 Dodge Ram 1500, 5.2L V8, 235,000 miles. Auto trans, 4WD. Plenum gasket failure is a well documented pattern failure on this series of Chrysler engines due to a mismatch of metals between the manifold and plate which expand at different rates and eventually force the gasket out.
The blown plenum gasket was replaced with a Hughes Engines plenum repair kit, including new plate, bypass hose, all 3 manifold gaskets, all new bolts, and a new thermostat. Oil was changed. There is a leak in the cooling system as I can hear the the heater core making noise, but the truck doesn’t overheat and the heater works so, unless the air is getting in from another vacuum leak, this is irrelevant.
I have a code scanner, there are no codes. (It had 9 when the gasket was blown, P0300 through P0308) The exhaust was dangerous to breathe when the oil was being burned, but now that it’s fixed you can’t even smell it. The mechanic who replaced the gasket said the plugs were fine, he pulled them all and they didn’t have carbon build up. It is NOT in limp mode, and it only hesitates in second gear. It revs all the way up at WOT with no problems. It used to shift rough on occasion, but since the misfires are fixed, it doesn’t seem to be doing it anymore.
I thought a new cat could be bought for less than $100? I can get it welded on for free. Where does this $500-$1000 come from? I don’t live in the democratic republic of California, so anything EPA approved will do.
I had a very similar problem on a 99 saturn 1.9l with 225K. The previous owner had replaced the cat. The intake gasket was blown and one coil pack was bad so it had rich exhaust (dead miss) for an extended period of time. The EGR brings this rich exhaust back into the intake and gunks up the EGR and IAC as well as sensors. I actually had soot coming out the tail pipe.
Cleaned the EGR, IAC and sensors assoicated with the intake and it runs fine now. It does burn about 1qt of oil every 1000 miles currently. I’ll probably address that later.
Don’t rule out a transmission problem, this could also contribute to the vibration.
Solving Performance Problems 1
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Re Performance Problems
[quote=”LJ11194″ post=37148]1999 Dodge Ram 1500, 5.2L V8, 235,000 miles. Auto trans, 4WD. Plenum gasket failure is a well documented pattern failure on this series of Chrysler engines due to a mismatch of metals between the manifold and plate which expand at different rates and eventually force the gasket out.
The blown plenum gasket was replaced with a Hughes Engines plenum repair kit, including new plate, bypass hose, all 3 manifold gaskets, all new bolts, and a new thermostat. Oil was changed. There is a leak in the cooling system as I can hear the the heater core making noise, but the truck doesn’t overheat and the heater works so, unless the air is getting in from another vacuum leak, this is irrelevant.
I have a code scanner, there are no codes. (It had 9 when the gasket was blown, P0300 through P0308) The exhaust was dangerous to breathe when the oil was being burned, but now that it’s fixed you can’t even smell it. The mechanic who replaced the gasket said the plugs were fine, he pulled them all and they didn’t have carbon build up. It is NOT in limp mode, and it only hesitates in second gear. It revs all the way up at WOT with no problems. It used to shift rough on occasion, but since the misfires are fixed, it doesn’t seem to be doing it anymore.
I thought a new cat could be bought for less than $100? I can get it welded on for free. Where does this $500-$1000 come from? I don’t live in the democratic republic of California, so anything EPA approved will do.[/quote]
The 500$-1000$ Depends of wear you are and of course the shop you go to…
Iv got a buddy who does the exhaust work for cheap but if you go to discount tires they want 300 when he wants 65$…. The saying (You get what you pay for is not always true)
Isnt that truck running platinum plugs???
If so there is no sure way to tail if the plugs are failing or have failed…
They are not like the copper plugs wear you can just clean them and reuse them…it only hesitates in second gear. It revs all the way up at WOT with no problems.
Sounds like a fuel devilry issue… Theres not as much demand for fuel when just reving a engine(Not as much work being done) But when you are in gear there is more work/load on the engine and – Issues like this can make there selfs known.Is the truck shuttering??? (Like when you take off in a slandered and dont apply the gas right) Kinda like a engine bog???
This is starting to sound like a bad reading or the wrong info being given to the computer. Give us more detail plz sir….
Does it do it when its warm or cold or both…Have you check your crank position sensor – cam position sensor… Im wounding if @ 2000 rpms something is get vibrated just right and causing a bad reading?
Thinking about it.. It sounds like a lack of fire to the plugs or a timing issue.
Have you check your timing???Well I just found out that when you have the engine under very heavy load, like starting out on a steep hill, it still pings a bit, but nothing like before. I think it’s still running rich because the computer hasn’t adjusted the fuel trims yet. I don’t have a scanner with live data to confirm this, though. And it wouldn’t necessarily cause it to hesitate. I’m thinking I should change the plugs, whether they’re clean or not. There’s no reason for the timing or fuel filter to be bad, this issue clearly started when it was burning oil and it hasn’t gone away. When I said it revs all the way up at WOT, I meant in gear. If you floor it, it takes off. If you just give it a little gas (say accelerating from 35 up to 45) you need to make it kick down or it won’t rev. It does it both warm and cold.
I could try to get a video of exactly what is happening later if that will help.
[quote=”LJ11194″ post=37242]Well I just found out that when you have the engine under very heavy load, like starting out on a steep hill, it still pings a bit, but nothing like before. I think it’s still running rich because the computer hasn’t adjusted the fuel trims yet. I don’t have a scanner with live data to confirm this, though. And it wouldn’t necessarily cause it to hesitate. I’m thinking I should change the plugs, whether they’re clean or not. There’s no reason for the timing or fuel filter to be bad, this issue clearly started when it was burning oil and it hasn’t gone away. When I said it revs all the way up at WOT, I meant in gear. If you floor it, it takes off. If you just give it a little gas (say accelerating from 35 up to 45) you need to make it kick down or it won’t rev. It does it both warm and cold.
I could try to get a video of exactly what is happening later if that will help.[/quote]
You steal need to check you timing… You could have a stretched…
Pinging under a load is a good sign of a timing issue or a fuel delivery issue.
Check your timing.
Change the plugs if in doubt.According to my factory service manual I need special tools to replace the timing cover… guess I’m not doing that. Being an OHV engine I don’t think I can even get to it without removing….everything.
[quote=”LJ11194″ post=37299]According to my factory service manual I need special tools to replace the timing cover… guess I’m not doing that. Being an OHV engine I don’t think I can even get to it without removing….everything.[/quote]
Leave it to dodge lol…
Wear are you located??? Pm me.
Bud are you sure you cant get a timing light on the engine to check timing???
You should be able to put a timing light on the truck any fluctuation in timing will tell you if you have a timing issue…
Iv seen a few truck wear the Dizzy will wear out and the dizzy rod will have wable to it.. RARE.Theres author ways to check for a weak or lose timing chain…
The only way to check the chain itself it to measure the amount of slop in it. Some manufactures have specs for this. The problem is that you have to dismantle the front of the engine to get to the chain to check to see if the chain is within specs. There really isn’t any manufacture recommended service interval for timing chains either. On distributor ignitions you could move the crank back and forth while watching the rotor on the distributor to tell if the chain was sloppy, but that isn’t really accurate. Engines with OHC, you really don’t want to be rotating the engine backwards anyway.If you want to get really technical, you could theoretically use a scope to see how stretched a chain is. As the chain stretches the cam and crank timing move out of sync. If you have a vehicle that has a cam and crank sensor and you suspect maybe the chain has stretched beyond tolerance, you could measure the variation between the cam and crank to see how far they are apart or use a pressure transducer to monitor cylinder pressures.
Lets not stress on this for right now. Lets check the basics and see if we can find any thing out of spec…
One thing you might try… If this is a tranmission issue most likely the issue will be LEAVING 2nd and going into 3rd…
See if you can recreate the issue in any other gears…. 1 3-4-OD
Shift into 2nd from a stop and take off and see if it happens- Lets just see.Have you changed your trans filter/fluid?
On old trucks if the engine was running right and vacuum was off the trans may not shift right… This maybe a simple fix we just have to find it.
Ok so iv been running threw alldate looking for recalls and other issues with this year truck….
Does your truck ever whine in reverse when its cold???
There are a few recalls on the trans that year but they appear to affect 3rd gear and up.
There are some other issues that could affect the trans as well be not the trans fault.
Bro sorry for my poor spelling.
I hope Im helping.I’ll see if tomorrow I can get it to hesitate under any other conditions but so far it hasn’t. Trans fluid hasn’t been changed, I plan to do it once I get an evacuator pump. Theres no drain plug and I’m not dropping the pan while it’s full of fluid. It shifts fine, this really seems like an engine issue. Especially since it was the first symptom of the blown plenum and it remains afterwards. As the plenum leak got worse it would do it all the time. Maybe just convenient timing, I don’t know, but I have trouble believing it’s not related.
You are helping dude, any input helps. No whining from the trans at all. It’s got a Jasper transmission, the original crapped out under 100,000 miles. The 46RE just isn’t very good but this aftermarket one improved on Chrysler’s alot.
Ummm. Makes since. Well a plenum leak is a vacuum leak. Maybe theres more vacuum leaks some wear…
Go get you a can of carb cleaner… WARNING DO THIS ONLY WHEN THE ENGINE COOL.
Spry the carb cleaner around any vacuum leaks. Spry around the plenum as well. Maybe the plenum did not seal 100% or maybe its warped.Get you a spry can of sea foam and spy it down the throttle body.(SPRY LIGHTLY – THE TRUCK WILL TRY TO DIE AND YOU WILL SEE WHITE SMOKE) after you have spryed for sometime take a look around the tail pipe area and see if there any black suds around the area…
The area of the plenum where the blown gasket was is inaccessible, there’s two intake manifold gaskets on either side and those are also brand new. I’ll spray around with a bottle of water first before I spray flammable liquids at my engine lol.
I know what sea foam is but I don’t fully understand what it does. Would it be cleaning any remaining carbon out of the intake and out of the cylinders?
I don’t think seafoam will cure anything, it can’t hurt, but I don’t think it will help. If you’re concerned about flammable liquids then perhaps you could fill the intake with smoke or use some other method. Tracking down vacuum leaks can be tricky at times but I find that it is the cause of many performance problems especially misfires.
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