engine changed in p38 2.5 but now changing gear at 4000rpm lowest .......:(

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majorpayne

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hi, really puzzled so help would be great! i have just changed my engine in my p38 whats a 1994, it was a strait swap. but now it wont change gear till it hits 4000rpm. now heres where it gets tricky i cant plug it in as it used to be a petrol and the plug does not work. it was the first engine change i done on a auto and im no mechanic and dident know u had to unbolt the torque converter so that came out with engine, so put it back on, couldent see any damage. it looked like it could only go on one way so i was happy with that. the only difference is the new engine is newer but not sure the age, it has a egr valve on it what it blocked but cant see how that would effect gear change. gearbox oil is high from when i re-filed it but cant see that would prevent it from changing normal everthing is smooth just have to drive it like i stole it, and im getting about 10mpg nailing it everywhere. any ideas would be great, thanks
 
wammers said:
Can you say what exactly you have changed, what petrol engine did it have in?
Click to expand...
Didn't spot the Petty to Oil part...

Hmmm yep errr....hmmmm...

If the box remains the same I can only imagine it was a 4.0 as the Diesel and the 4.0 had the same box....but I thought you had to be careful with the TQ convertor as you can damage the GB pump (??) if done incorrectly!
 
Last edited:
Petrol gearbox has a different ECU and a totally different shift pattern. What's the plug he can't plug in. Bit of a cock up if you ask me.
 
I have the same issue, I've just changed the engine in my P38 Dse after throwing a piston out the side of the block:( when this happened a "Gearbox fault" came up on the dash and after fitting the replacement engine it starts and runs fine (no faults displayed on dash), but will not change gear till 3800/4000 revs and kick down no longer works.
I understand it could be stuck in a limp home mode or maybe the new fuel pump needs coding to the ECU or maybe I damaged the oil pump during the engine change? but I'm really not sure, any ideas welcome.
 
BTW- Gearbox oil is fruity fresh with clean filter at correct level, no faults show on hawkeye, 'D' is displayed on dash as it should be, all gears work but will not change until 2nd gear = 3500, 3rd = 3800, 4th = 3900. Seems to work ok in low box. Replaced an auto diesel with a manual diesel engine that I converted to an auto before fitting.
 
hi, it used to be a petrol once apon a time but the engine i had in it overheated and that was a diesel, so this will be 3rd engine. when i brought it it was diesel was once petrol. old diesel engine ran fine with gearbox but changed engine and next day i had this gear change problem, sounds the very same as 38PROBLEMS one. all i can think is its electrical ecu prob, but cant plug it in as plug is not connected. will lower gearbox oil level to see if that helps
 
38Problems said:
BTW- Gearbox oil is fruity fresh with clean filter at correct level, no faults show on hawkeye, 'D' is displayed on dash as it should be, all gears work but will not change until 2nd gear = 3500, 3rd = 3800, 4th = 3900. Seems to work ok in low box. Replaced an auto diesel with a manual diesel engine that I converted to an auto before fitting.
Click to expand...
Stuck in sport mode?
 
pretty sure tq converter wasent damaged, it worked fine before engine change and differnt now, think this engine could be a dhse and old one was dt first ones so maybe it need plugging in some how, maybe car electrician if they exist ?
 
no comes in and out of sport mode but makes no diff, when driven in sport mode before engine change it changed lower then 4000
 
I am going to change the engine wiring loom for the one of the previous engine tonight, at least that will eliminate a wiring issue.
 
majorpayne said:
pretty sure tq converter wasent damaged, it worked fine before engine change and differnt now, think this engine could be a dhse and old one was dt first ones so maybe it need plugging in some how, maybe car electrician if they exist ?
Click to expand...
Engines are the same but the ECU's for the engine are different depending if there is an EGR and MAF fitted. Should not cause a problem as long as the ECU matches the engine set up unless there is a compatibility problem between the engine ECU and the Auto ECU.
 
ok thanks datatek, getting abit technical for me so may have to take it somewhere who knows about electrics on them
 
You said in your first post is used to be petrol and you have fitted a Diesel....

Diesel Gearbox ECUs and the Petrol Gearbox ECUs have different shift patterns as Wammers has already pointed out...

Then above you say this engine is dHSE and the previous was a DT...both of which are Diesels...so what is it you have changed from what to what??
 
it was factory petrol 4.0, then when i brought it someone had already changed it to diesel. and that diesel engine blow up on me so put another diesel in it, so all set up for diesel.
 
I've just changed the wiring loom and left hand sensor on the head (toward front of engine) and hey presto, all is back to normal now, took about 4 hours to do the work, air manifold off, fuel pipes off, battery off etc. I changed the sensor as it only had 1 pin, the sensor on my original head had 2 pins. I am very happy bunny now :)
 
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