Good luck Here is an email to merlin to recap my own problems - and not to steal your thread but may give ideas.
Merlin. You have a good reputation among the VX.info people of which I am one and so I was hopeful that you might be willing to comment on this problem.
5 weeks ago my transmission lost 3rd and 4th gears so I brought it to a local transmission man with a good reputation. He rebuilt the trans. When he was done the engine had a misfire. I pulled the codes: random misfires and o2 sensor S1 B1. I replaced the o2 sensor. Still had the problem. over the following 2 weeks I went crazy trying to fix this problem. and here is what I did.
1. replaced fuel filter.
2. seafoam in tank, twice.
3. replaced EGR valve.
4. replaced IAC
5. replaced throttle position sensor.
6. cleaned throttle body while in place.
7. replaced air filter.
8. Cleaned MAF sensor.
9. Checked fuel prssure on the rail.: 38 key on. 32-34 engine on. Fuel release dropped it to 20 while I filled 2/3 quart of fuel in 30 seconds. the engine idled fine.
10. replaced ALL O2 sensors.
11. replaced all spark plugs.
12. checked resistance on all coils: good.
I did all these things out of desperation, stupidity and the because after clearing codes eventually a new different code would set. Like a different o2 sensor, but always random misfires.
2 weeks ago I brought it back to the trans man. He has been going over it and is stumped. He replaced the MAF no results. He is now getting a TPS code!!. We think ECU problems now.
The problem is roughness and loss of power at lower rpm and lower speeds. The character or degree of it is intermittent. I have gone miles thinking its fixed and then later in the day go somewhere with it rough as heck. If one keeps it at a constant 40mph there will be a subtle loss of speed and power - then it senses the problem and kicks in and overcomes. when it is doing this i can press the excellerator pedal a little with no reponse and hold it there then after 5-10 seconds it kicks in and throws me back in the seat with power and smoothness. It will run GREAT at high speeds and rpms.
If you have any thoughts we have not covered please let me know. Do you think an ECU is next??
Here is what Merlin says:
Back in the beginning I would’ve guessed intake manifold gaskets- very common on these engines and a common cause for random misfire codes. They also mainly impact low-speed (low vacuum) driveabilty. But now that you’re getting different/strange codes, I would be concerned that you have an engine wiring harness and/or ECM issue. I would have your technician clean and lubricate all the electrical connections he had to make, as well as cleaning and checking some of the harness ground connections- even triple-check the cleanliness and condition of the battery terminals. In a misfire situation, you might also want to have the compression tested- a leaking head gasket will cause a random misfire as well and show up as low compression on one cylinder- although that doesn’t seem quite as common on these engines.
Sorry you’re having so much trouble…I certainly wish you luck though.
Talked to my trans man today and he thinks my exhaust is plugged.....
and I'm going to put a smiley after I say this;Even though I haven't had my VX in weeks now!! Errrrr!. I wish you well figuring yours out.!!
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