QuestionWoudl the TPS cause the misfire only on the left bank? I know of several problems with the GEMS motors and the 4.0 in perticular. One is that they drop cylinder liners on 7 and 5 mostly. I'm not loosing much coolant (The expansion tanke is down an inch in 400 miles) and it's not smoking. I have not checked the plugs for being "Too Clean" yet as i'm wearing a suit every day.
The other is that when the computer thinks there is a "Issue" with vehicle speed it shuts down the left half of the injectors until things come into line. I'm not sure thats it as it runs rough at idle when it's fully warmed up and also hesitates badly off the line until it gets to 3000 rpm.
I'm putting my cash on clogged injectors from the known tank recall. The stock gas tank had a paint desolving issue internally that clogged everything. But why only after it warms up?
Remember, this is a GEMS system, not a Lucas hotwire like your 3.9. Everything is different except the block design and intake manifold/water pump.
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Followup To
Question -
OK, I have read and done 90% of the things people have told me to do about my 1996 5-speed discovery with 95k on it. I just did the valves on both sides less than 2k ago. Changed the MAF, VSS, wires, plugs, coil pack. Still has massive hesitation off the line after warm up. When the motor is cold it runs somewhat well. After 10-20 minuts, it starts to shake at red lights then hesitates massivly when I step on the gas until I reach about 3000 RPM then "Breaks Free" kinda and has decent power ther up until I shift. I'm not loosing water also if thats your next question. No knocking from engine or slapping.
Exhaust smells rich. Computer stores codes P1313, P1316, P0300, P0305 and P0307 (I know what they all mean).
The only thing I can think of is that I have injectors that are clogged when they heat up.
Another thing is that when it shakes REAL BAD at a light, the check engine light sometimes blinks. When it's blinking, the motor runs well for that moment. It even has torque off the line until it stops blinking and goes solid and the truck returns to crappy mode.
I suspect one of the cats is hollowed out on the drivers side. There is a large size welded patch on the bottom of the cat but I dont think that would be enough to cause the motor to sometimes be undrivable.
I have not connected the truck to a autologic or testbook as my local rover michanic robbed me in the past and I burnt that bridge.
Now what? I know GEMS computers cut off the odd cylinder bank at the first sign of trouble. I thought changing the VSS would fix this problem. I don't think it's fuel pressure as it runs well when it's cold. The pump would wig out all the time, no?
Help!
Answer -
Hi Craig,
that's a ---- load of work you've done on your Disco! Did you do all the work yourself? I can understand your hesitation to return to the dealer, especially if you've been burned before.
You may want to change the TPS (Trottle position sensor). My '95 Disco had similar problems and it turned out to be the TPS. Dealer also charged me to 'reprogram' my ECU but I have no way of knowing if that helped.
Best of luck,
JohnMc
Answer******************FOLLOW UP *********************
Hi Craig,
No, I don't think the TPS would affect only one bank but the description sure sounded like the problem I had with my TPS.
A LR mechanic once told me that if a cylinder sleeve(liner) ever drops you can wave 'bye-bye' to the engine. Nothing can be done.
I know the GEMS motors have more than their share of troubles. There is less and less adjustments that can be made without investing into a LR testbook. That's what I like about my 3.9 Disco! Having the GEMS system linked into the security system was a big mistake for LR. Trouble is ... we owners are the ones who pay for the mistakes.
It sounds like you're really going to need more than an OBDII reader for this. I wonder how much a dealer would charge just to have your Disco engine analyzed? Can't be more than an hour's labour charge and it could save you some money in the long run.
I was not aware of a paint desolving issue with the recall gas tanks. I am suppose to have my tank changed sometime this week. Now I have another worry when I drop off the Disco.
Its true about my 3.9...the TPS is prone to failure, the 02 sensors, the MAF and lots of wiring harnesses. Your GEMS engine has more diagnostic capabilities, however, you have less influence on how the engine runs. At least not without a testbook. How about 02 sensors? Have you tested them on a scope? www.roversnorth.com (Rover's North) has an excellent article on 02 sensors and how to diagnose engine troubles. Look into the DOWNLOAD section and copy the SUMMER 2005 catalog to your disc. The article is quite revealing and could be useful to you.
Best of luck with this,
JohnMc
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