2.9 jerks on freeway

[Zachalanche]

This just happened for the first time today. I was drivng my 89 up a moderate incline at roughly full throttle when the engine missed. in fact, it seemed to be a bit harder than a miss. the first time it happened I thought I might have hit a bump in the road, but it happened 2 more times roughly 80 miles later, and it definitely seems like either a momentary loss of fuel or ignition. all occurences were with the engine under heavy load in either 4th or 5th gear.

Anyone have any thoughts on this?

any suggestions - much appreciated.
thanks in advance.

 

[whale]

When I read the title, I thought you meant guys with 2.9L acting like jerks on the highway. LOL

Then I thought "But how?"

 

[shane96ranger]

Well, when I read it I thought "We have a lot more than 2.9 jerks on our freeway".

Back to the point - Zach, do you think it was engine or trans?

 

[Original_Ranger84]

Sounds like it could possibly be your TFI modual if you have one on the 2.9L

 

[Psychopete]

When was the last tune up? sounds like spark plugs are trashed.

 

[RyanL]

It might be something as simple as plugs or wires and you should get to that stuff replaced if it needs it so you can rule that crap out. It doesn't sound like a fuel issue to me, more of an ignition or electrical problem. The reason why I say it's probably not the fuel supply because you could even remove the fuse for the fuel pump and it doesn't suddenly die. I takes a few seconds for it to run out of fuel and then slowly dies off. Now I guess the jerk that you feel could possibly be the fuel supply kicking back in, but I doubt it. It's hard to say without being there to check it out in person.

 

[jrpdash9]

my friend had a 90 with a 2.9 5 speed (350xxx miles) and we where on our way from veo tech to work going up a good size hill.. he ran it at the full throttle to and it did the same thing.. it was the oil pump.... pain to change in a 4x4 with out pulling the engine but we barely got it. it could also be something in the ignition like the distributer composites


so check ur oil pressure then ur spark

 

[Zachalanche]

When I read the title, I thought you meant guys with 2.9L acting like jerks on the highway. LOL

Then I thought "But how?"

Nice! I'm pretty sure thats what people think when I try to drive my truck in the fast lane.

Well, when I read it I thought "We have a lot more than 2.9 jerks on our freeway".

Back to the point - Zach, do you think it was engine or trans?

Manual trans so I wouldn't think the trans could suddenly unload and reload without me using the clutch. I haven't noticed anything that would lead me to believ I'm about to lose any gears.

When was the last tune up? sounds like spark plugs are trashed.

New plugs cap rotor and wires last summer (10k miles ago). New O2 sensor 30k miles ago. everything else appears to be in very good operating order.

Ignition module is roughly 140k miles old.

 

[whale]

Actually, I had what you're describing happen on my 88. I agree with the sentiment to check your plugs and wires. In my case, I discovered that one of the wires was cooking on the manifold, causing the miss under load.

Will

 

[Zachalanche]

my friend had a 90 with a 2.9 5 speed (350xxx miles) and we where on our way from veo tech to work going up a good size hill.. he ran it at the full throttle to and it did the same thing.. it was the oil pump.... pain to change in a 4x4 with out pulling the engine but we barely got it. it could also be something in the ignition like the distributer composites


so check ur oil pressure then ur spark

The spark will be a pretty hard one to check since I would be looking for spark disappear while I am doing 70 on the freeway.

oil pressure never dropped on the stock gauge I will need to hook up a better gauge at some point, but all the lifters are staying quiet, and thats the first thing I would expect to hear on loss of oil pressure.

 

[Zachalanche]

Actually, I had what you're describing happen on my 88. I agree with the sentiment to check your plugs and wires. In my case, I discovered that one of the wires was cooking on the manifold, causing the miss under load.

Will

I'll do a quick visual check when I get home today. the jolt that I am feeling seems like the motor is completely shutting off momentarily, so I better make sure the coil wire is in good shape.

 

[jrpdash9]

ya but to loose spark going down the road there is a problem on idle that we dont see. it could be anything from a loose wire to a bad module that works fun at low rpm or low load. and ya his truck ticked like a sob when his pump went..

 

[RyanL]

Nice! I'm pretty sure thats what people think when I try to drive my truck in the fast lane.



Manual trans so I wouldn't think the trans could suddenly unload and reload without me using the clutch. I haven't noticed anything that would lead me to believe I'm about to lose any gears.



New plugs cap rotor and wires last summer (10k miles ago). New O2 sensor 30k miles ago. everything else appears to be in very good operating order.

Ignition module is roughly 140k miles old.

If you gave a few more details in your original post, it would have saved you from the inquisition. 140K on a TFI is pushing it to it's limits, especially if you didn't do a relocation.

 

[Zachalanche]

If you gave a few more details in your original post, it would have saved you from the inquisition. 140K on a TFI is pushing it to it's limits, especially if you didn't do a relocation.

no worries on the inquisistion, just wanted to hear what people had to say before I guided their answer the wrong direction. Your note on the TFI life inspired me to do some further research. I had no idea the failure rate was so high for that part. how do the aftermarket TFI's compare?

 

[RyanL]

no worries on the inquisistion, just wanted to hear what people had to say before I guided their answer the wrong direction. Your note on the TFI life inspired me to do some further research. I had no idea the failure rate was so high for that part. how do the aftermarket TFI's compare?

I really don't know, but I will say something; most OEM Ford parts seem to be superior to the imported crap which many of the parts stores pedal. I would say that the sensors, alternators, and starters last about half as long as the factory stuff if you're lucky. I touched the back of my TFI when I was under the hood with it running (I think I was in the process of relocating it and I had it floating there with the wires connected) and burned the crap out of my hand. It felt like I touched the exhaust manifold or something. I cracked my old one open and it has a circuit board encased in some sort of goo. I don't know why they get so damn hot; must be a design flaw. Anyway, I'm hoping that mine lasts a little longer with it solidly mounted on a heat sink with computer thermal paste on it. I even cut a square into the lower part of the air box and stuck the heat sink fins into it so it would have constant cooling (even when sitting still idling). I think that I came across a TFI made by one of those performance brands like Accel or MSD (of course right after I had bought my replacement) and I don't think that it cost too much. I haven't heard anything as to if it's an upgraded unit or just a carbon copy of the factory one.