Misfire Identification

[SplotchyAphid05]

Anyone have any advice on what could be causing a misfire after adjusting the valves. The first time I adjusted them it caused awful valve noise so I did it again and now its missing but it wasn’t before. Spark plugs are new, wires ohmed out good, distributor cap contacts were cleaned. The only noticeable problem that I can tell is the alternator isn’t charging the battery and there must be an exhaust leak. Also the cel isnt on only the rear abs light and battery light.

 

[Brain75]

Couple questions, distributor on a 2.9 is pretty rare, are we talking about the 1990 2.9 in profile?

Did you try looking for any codes in the computer? (OBD1 is a kind of a game with an analog voltmeter counting the sweeps).... procedure for it should be easily googleable or in the back of the haynes/chilton.

 

[SplotchyAphid05]

Couple questions, distributor on a 2.9 is pretty rare, are we talking about the 1990 2.9 in profile?

Did you try looking for any codes in the computer? (OBD1 is a kind of a game with an analog voltmeter counting the sweeps).... procedure for it should be easily googleable or in the back of the haynes/chilton.

Yes it is the 1990 but I will try and pull codes and update

 

[rusty ol ranger]

Couple questions, distributor on a 2.9 is pretty rare, are we talking about the 1990 2.9 in profile?

Did you try looking for any codes in the computer? (OBD1 is a kind of a game with an analog voltmeter counting the sweeps).... procedure for it should be easily googleable or in the back of the haynes/chilton.

All 2.9's had a distributor.

Is it missing only at idle? Under load/throttle?

If its at idle leave it run and pull plug wires one by one...untill you cant notice a difference in engine tempo, that will tell you what cylinder is missing.

If its under load id be checking fuel pressure and timing.

The valves on a 2.9 arent technically supposed to be adjustable. Yes they can be, but only after valvetrain removal.

The battery voltage could possibly cause a miss, though pretty unlikely, and an exhaust leak isnt going to cause one.

 

[2011Supercab]

and an exhaust leak isnt going to cause one.

But it could sound like one even if there is no miss.

 

[rusty ol ranger]

But it could sound like one even if there is no miss.

true

 

[gaz]

@SplotchyAphid05 , "1990 2.9l,"
You state that your engine trouble started after you adjusted the valve train:
• do you understand the principles of hydraulic lifter preload adjustment?
• what procedure did you follow to accomplish the
• you state the your 1st attempt went south resulting in increased valve train noise, did you learn why?
• did you thoroughly clean and inspect the rocker arms, rockers and push rods for servicablty?

• did you change the timing?

 

[SplotchyAphid05]

@SplotchyAphid05 , "1990 2.9l,"
You state that your engine trouble started after you adjusted the valve train:
• do you understand the principles of hydraulic lifter preload adjustment?
• what procedure did you follow to accomplish the
• you state the your 1st attempt went south resulting in increased valve train noise, did you learn why?
• did you thoroughly clean and inspect the rocker arms, rockers and push rods for servicablty?

• did you change the timing?

I did time the engine even with the miss to see if that fixed it and It didnt but I will link the two videos I have of it running with the valve train noise and with the miss to see what you hear but I did not fully disassemble the the rocker arm assemblies but I used a solvent tank to clean them. The procedures ive tried are what the book says with getting all cylinders to zero lash then at tdc on the compression stroke and turning in 1.5-1.75 rotations the next one I tried involved doing the math about how many rotations to turn the screws, the next method I tried was paying someone and the last method I tried was a video from vice grip garage. I think it has something to do with the valve lash though because with the initial adjustment there was no miss just tons of valve noise and with every adjustment after that ive been able to remove the valve noise but it comes with a miss.

Video with no miss

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Video with miss

- YouTube

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youtube.com

 

[SplotchyAphid05]

All 2.9's had a distributor.

Is it missing only at idle? Under load/throttle?

If its at idle leave it run and pull plug wires one by one...untill you cant notice a difference in engine tempo, that will tell you what cylinder is missing.

If its under load id be checking fuel pressure and timing.

The valves on a 2.9 arent technically supposed to be adjustable. Yes they can be, but only after valvetrain removal.

The battery voltage could possibly cause a miss, though pretty unlikely, and an exhaust leak isnt going to cause one.

It is at idle but it doesn’t miss for the first few seconds of starting if its been sitting for a bit but I did time it with that miss and I did only have to adjust the valves because this is after rebuilding her and just trying to get her drivable again but I will start pulling plugs to see if I can ID the troublesome cylinder

 

[Shran]

That sounds horrible. I second Rusty's advise about pulling plug wires to at least narrow it down. Wondering if you have a collapsed lifter or something.

What did your rebuild process entail? Cylinders bored, new pistons, cam, everything inspected, etc? Some context on that would be helpful, I have had people claim to have rebuilt engines and in reality they just painted a dirty engine... "rebuilt" is used very loosely.

 

[SplotchyAphid05]

That sounds horrible. I second Rusty's advise about pulling plug wires to at least narrow it down. Wondering if you have a collapsed lifter or something.

What did your rebuild process entail? Cylinders bored, new pistons, cam, everything inspected, etc? Some context on that would be helpful, I have had people claim to have rebuilt engines and in reality they just painted a dirty engine... "rebuilt" is used very loosely.

Bored .040 over new pistons, cam, lifters, water pump, timing set, bearings all the way around and im sure I might be missing something but thats the majority of it

 

[Shran]

Well that's good

Did you soak the lifters in oil before installing them? IIRC, that is required. I'm assuming you have good oil pressure?

Wonder if it would be worth doing a compression test to see if a valve is staying open. The way it's acting makes me think that a valve or valves are not opening at all or not nearly enough when you have them adjusted looser.

 

[SplotchyAphid05]

Well that's good

Did you soak the lifters in oil before installing them? IIRC, that is required. I'm assuming you have good oil pressure?

Wonder if it would be worth doing a compression test to see if a valve is staying open. The way it's acting makes me think that a valve or valves are not opening at all or not nearly enough when you have them adjusted looser.

The oil gauge on the truck reads good pressure and im pretty sure I soaked them this is a project Ive been messing with on and off for the last year and some change but Ill do a compression test after the wire pulling test I just got home to try it

 

[Slyronious]

Sounds like the valves are too tight with a loss of compression. Or you may have a fouled plug from oil getting into the cylinder

 

[SplotchyAphid05]

Well that's good

Did you soak the lifters in oil before installing them? IIRC, that is required. I'm assuming you have good oil pressure?

Wonder if it would be worth doing a compression test to see if a valve is staying open. The way it's acting makes me think that a valve or valves are not opening at all or not nearly enough when you have them adjusted looser.

Compression test results
Cylinder 1- 150psi
Cylinder 2- 150psi
Cylinder 3- 149psi
Cylinder 4- 153psi
Cylinder 5- 140psi
Cylinder 6- 135psi

and the spark plug wire test cylinder one didnt really seem to change it honestly i didn’t notice massive differences in that test except maybe my wires are bad because i could wiggle them and change how the engine was running even though they ohmed out well