'88 Dakota running poorly...need new injectors or valve job?


#1

1988 Dodge Dakota, 239 V6 (TBI), 233,000 mi. Problem is thus: truck started having trouble starting up, followed by stumbling at WOT, followed by stumbling at >2/3, etc…until it could hardly drive down the road. I diagnosed “lean burn” (due to the fact that ether would smooth out the resultant rough idle) and replaced the fuel pump , pressure regulator and filter, to no effect.

Truck was then dropped off at auto repair, where they replaced a timing chain with too much slack. They reset cam timing, and found low compression (50#) on the 1 and 5 cylinders, and diagnosed bent valves as causing the problem (based on symptoms only).

Right now, it’ll idle just fine, and run marginally under “open loop,” but will begin to stall out about 3 min after startup, particularly under load. Basically, the only way I can get it to get down the road is to pump the throttle in drive, and I’ll get some “oomph” out of the engine. I managed to get somewhat better running by deliberately disconnecting the coolant temp sensor in the effort to force rich running.

After a trying 2 mile trip home, it idled rough that (again) smoothed right out with a squirt of ether.

I diasgree with the diagnosis; I think the main problem is still lean running (due to symptoms…in particular, I think that a truck with 4 of 6 cylinders working would run better than this!) What I think happened is that one of the two TBI injectors failed (particularly the one feeding the bank with the low compression). I think the low compression is likely a side-effect of sustained lean ops acting on the exhaust valves.

So, I soaked both TBIs in solvent. I re-installed, but ran out of battery quickly, before I could get restart.

Should I feel confident enough in my diagnosis to pay $230 for 2 new injectors? (Assuming the “cleaned” ones won’t work). Right now, I need to get the truck running well enough to move it 7 miles: I’m in a motel parking lot and cannot remove a cyl head until I get to my new home. I cannot afford to do both the injectors and ship the head off this month, so I need to do the TBI, if it’s likely to get my truck to some semblance of normalcy.


#2

If it were me, I’d have it towed or drop the driveshaft (if it’s an automatic) and have someone help me tow it with a rope (slowly and during late night or very early morning hours with little traffic) to get it home before I’d spend one penny on it.

Before assuming valves are the only problem I would consider the compression readings on the cylinders that are not low. If those readings are low and possibly involve piston ring problems the you should consider another used engine or a rebuild; probably the former.

Being curious of course, what were the readings on the good (?) cylinders?