87 DL- Boneyard time? ( hesitation, bucking, skipping)

Harry von Zell · Post by **Harry von Zell** » 03 Nov 2007, 09:27

Findings : SSDD

Blasted cleaners through engine, no improvement. Good mechanic, but unable to locate problem.

87 dl skips, bucks and chokes off a dead stop AND while driving with soft pedal pressure. If I floor it it accelerates normally, but returns to skipping etc. when I let up on the gas pedal. ONLY happens AFTER engine warms, No problem when driving cold

Replaced AMM, fuel filter, in-tank and main fuel pump, CAT, fuel relay, 25 amp fuse.

In short, I've spent way too many $$ on an 87 at this point. Car is overall solid, but enough is enough.

Unless I can fix this it's boneyard time.

Driving in city traffic, like this is dangerous.

Thanks, Harry

dripcandles · Post by **dripcandles** » 04 Nov 2007, 18:42

I just bought an 87 740 that has the same symptoms. I will be trying to figure mine out as well. I spent awhile searching the forum and I am thinking I will start with checking for vacuum leaks,then the o2 sensor, then the fuel pressure regulator, then try to figure if an injector is bad. My car blows black smoke, so I know there is a specific problem. Does your car blow smoke? If it has the same problem I will keep you posted on my progress.

Harry von Zell · Post by **Harry von Zell** » 05 Nov 2007, 06:56

No, I'm not blowing any smoke. Seems like typical AMM symptoms.

Having put so much into it now, I'm very hesitant to keep replacing things at random, without some confidence that we know what's causing the "bucking".

My AMM replacement was a used one, and I'm thinking it may be "bad" since the symptoms are so related.

I'm going to try wires and distributor cap next.

I've had very high NOX readings, for about a year ( replaced CAT) and I think the high NOX and "bucking are related.

I also think that the fact it only happens when the engine is WARM, is significant.

Y\The quest continues........

sony2000 · Post by **sony2000** » 19 Nov 2007, 16:59

A temperature sensor is in error when warm.

Harry von Zell · Post by **Harry von Zell** » 20 Nov 2007, 07:19

DEFINATELY Temperature driven problem. We're going to test w/ propane for leaks and the manifold gasket this week.

Temp Sensor IS my guess.

Plugs
Wires
Rotor
AAM
Fuel Filter
CAT
25 amp engine fuse
In-tank Fuel Pump
Fuel Pump
Fuel Sensor(the module above the passenger side leg space.)

Expensive trip for no results.

Thanks,

Harry

wojeepster · Post by **wojeepster** » 20 Nov 2007, 20:10

The hall pickup in the distributor has very fine wire in it. If one of these wires breaks frequently it will work when cold and fail when it warms up. You can get a can of cold spray at radio shack and cool down the pickup if it starts to work again you have located problem. This is a known problem on the 740 and there is a writeup around here someplace. I havent heard of a 240 with this prob, but that is what I would suspect. Problems can be difficult to deal with and understand but just think how great you will feel when you solve the puzzle.