Engine Issue

[av8or]

New guy to the forum and have an engine issue I'm trying to zero in on. Have 1999 Disco I with 127,000 miles. No major issues to date, thank goodness. However, recently the engine has developed a stumble at road speed, starts around 1500-1700 rpms. It idles okay with no apparent misses and revving the engine not under load results in a smooth rev up. I have replaced the spark plugs recently and we pulled them all for a look and nothing jumps out at you...appear normal.

I put a can of BG44K and it seemed to diminish the roughness sometimes, but I'm beginning to think it was my wishful thinking. I thought I'd wait until I had run a tank of fuel through the engine before doing it again. The mechanic who sells the stuff says not to over use. Also thought I'd use it with half a tank of fuel versus the nearly full tank of fuel I did the first time. Additives I'm never really sure about, but some people seem to sing BG's praises.

Anyway, I have been reading with great interest some of the comments from "joey, and beemer and others" about injectors and am beginning to think I've got at least one that is not working properly. I'm thinking its okay for idle and lower rpms, but under load it just isn't doing its job. Would appreciate insight. For injector servicing I found this site and wonder what you guys think.

injector-rehab.com

Thanks,
Gibson
Newnan, GA

 

[Maddie]

Have you checked fuel pressure, fuel filter, fuel pump?

 

[av8or]

Fuel filter was just replaced. But no on fuel pressure and fuel pump. Fuel pump cycles as always on initial switch on just before start. I'll see if my friend has a pressure gauge we can check fuel pressure with.

 

[Disco Mike]

Do you have any fault codes, have you replace the grey plug wires?

 

[av8or]

I don't have any fault codes and I have replace all the spark plug wires with wires I got as a set for Atlantic British. Not sure what you are referring to as "grey" wire.

 

[joey]

Also check and see if down shifting from Drive to 3rd fixes the issue.

 

[av8or]

I found the real issue. Bad U-joint on rear of front drive shaft. U-joint was totally shot and just about ready to come apart. Thanks for the input.

 

[Disco Mike]

So what have you done about the drive shaft, are you going to rebuild or replace it?
So, is your engine running OK now?

 

[addison]

Its fact think if your vehicle have lower rpm and you are go through high speed and long rout like 1500-1700 km then its very bed for engine because of your rpm engine will automatically got load and efficiency will decreased day by dy so you have to check that first and keep to maintain that thing.

 

[av8or]

Mike, the engine is fine. Don't think there ever was an engine problem, which is probably why I could never get any engine roughness when the vehicle was sitting still. The drive shaft was fine, new u-joints went in like a charm. The noise I was experiencing would start around 1500 rpm and would vibrate and feel like the engine was missing, it would go away when the accelerator was decreased, although I would feel some of the same vibration when there when any engine braking. Two sides of the u-joint (opposite sides) were totally missing the needle bearing. I began hearing a noise that sounded like a fan belt squeal, I guess that was the needle bearings making their last gasp. I began thinking there was a transmission issue after I replaced the idler pulley bearing. I crawled under the truck looking around, then pushed on the driveshaft when it moved the big light bulb came on. Thank goodness my buddy had a press, made the job quite easy.