Sporadic Hesitations

[wilma]

I have a 97 Discovery that has 97k miles. I bought it at 55k and have had a shopping list of work done to it. New valve lifter arms, new fuel pump, new head gasket and new exhast manifold to name a few, all warranty work Lately the truck hesitates for three to five seconds then picks back up again for three seconds and then repeats. Then it will stop and run perfect for the next 300 miles. The last time this hesitation occured the check engine light came on. The fault was a random misfire and it also recorded a knock sensor being set up. I put in new plugs and wires and it ran fine for 200 or so more miles and then it hesitated again and the check engine light is back on. The local Land Rover service manager says it maybe excessive carbon build-up and I may need a $2300 head/valve job to fix the problem. When asked if he could guarantee this would fix it, he couldn't.

Could this be a bad EGR valve, solenoid, temperature sensor or EGR ECU? It is so random and seems if it was carbon build-up it would be a chronic problem. I'm not about to lay down $2,300 if they can't guarantee the repair.

Does anbody have any ideas of what could be causing this random hesitation?

Thanks

Troy

 

[discomike]

Troy,
Have somene hook in with a scanner and go drive, see what shows up.
If it is carbon, that is something you can help clean up with some good gas treatments, what gas and octane do you use?
If you have any work done by the dealer, they have to warranty it for one year and unlimited mileage.
Mike J.

 

[wilma]

Mike,

I use 87 octane gas but add STP gas trreatment to each tank. Is there something better to use? What is the best product to cleanout the carbon buildup? Seafoam? I have seen it, but never used it. Do you just dump it in the gas tank?

 

[joey]

Also at what speed is this issue happening? If over 50 MPH, then try to put in third gear when this happens if it goes away, sounds like the VSS (Vehicle speed Sensor) may be bad. 87 octane could also be the issue... the rover requires 91 or higher if I recall correctly.

Seafoam... three cans.. one in tank, one in oil, and one in the intake vacuum hose (right at the throttle butterfly). This will help alot as well.

 

[texasrover]

91 or higher... you recall correctly!

I would give the seafoam a try. This is a cost friendly try!

I have not put the stuff in the oil or the intake before, I must try this. Is it best to run it for a while in the oil right before you change the oil or is it okay to leave in the oil? Basically, are you using it like a flush?

 

[joey]

Best to put in oil about 100 miles before oil change (IMHO).

 

[ricklandrover]

Had the same problem, it actually turned out that it was my spark plug wires, pay a little extra for good ones if you are going to replace them because I bought vheap ones at first and it didn't fix the problem but once I bought good ones the hesitation was gone!