P38 Idle up and down 2000 to 3000!

Hi Guys, Hope someone can help me.

I inherited a P38 from my dad several years ago when he died, and up to recently it has been a good old bus. Ultra reliable and passes MOT every year. Recently after a period of not being used (even with LPG he is expensive to run compared to my MG!) the battery went dead and he has started to run weirdly ever since.

Essentially he starts fine usually, although sometimes I have to pump the throttle to get him to fire (usually more when hot), however when started the idle is too high - say 1500 to 2000. I did some googling and noticed that the IAC and MF can get gunked up if not used much so I checked and sure enough they were gunky. So I cleaned them both with carb cleaner and Electrical contact cleaner and refitted them once dry.

Started him up and..... idle was faster! GRRR Now he starts at about 2000 and goes intermittently up to 300 then after a while drops down to 2000 again (sometimes down to 1500).

Anyway I did some more poking around and took off the Throttle Position Sensor and one of the little plastic lugs in there has vanished - so I'm guessing it may not be returning properly or something - giving the wrong resistance and confusing the hell out of the ECU.

I tried to google the part number on the unit I took off (7E15A 80481A) but found nothing. One on eBay I saw looks completely different (Item 160664803035) despite saying it is for 'LAND ROVER RANGE ROVER 4.6i 4554cc 16v 225bhp 09/1994 On '!! I was going to try to do a famous botch with a blob of araldite on it to make up the lug but now I can't find my tubes of that now just to annoy me even more! LOL

Any help would be most appreciated.

Thanks,
Adam

I had the same fault when i forgot to reconnect the hose from the air cleaner to the MAF correctly.

Nicktrackside said:

I had the same fault when i forgot to reconnect the hose from the air cleaner to the MAF correctly.

Click to expand...

Wish it was that as it would be a quick fix - alas that is well and truly clipped together properly!

Hope you get this sorted.

I found a replacement TPS on eBay - awaiting my mate who owns a diagnostic system to come back to me to see if he is able to reset things before i buy it.

Fingers crossed!

OK been a fiddling again this w/e as discovered the MOT has ran out anyway so I cant drive him!

I popped the IAC off and switched on the ignition with it connected and nothing happened to it, so I switched ignition off and BOING!!! The bloody piston thing unwound itself and shot off into the flower bed! GRRR Managed to find it and the sleeve and it seemed to screw back in a bit but not fully.

What to do I thought - so I put it in place on the throttle body and screwed it back as far as i could then started the car. The stepper motor kicked in and it wound in some more so I screwed it fully back. Now I am wondering if its the IAC that is faulty in some way too?

The other odd thing is that if when it's all back together and running (now at about 1800 after the flying IAC piston episode!) I pop my foot on the throttle VERY slightly the engine drops to what I imagine idle should be. If i push further it revs just fine with no flat spots or anything.

Oh and the other thing I noticed is that the banking plug from the adjuster for the base idle is missing - so I guess this poor thing has been fiddled with previously (it did live in Malaysia for the first part of its life apparently!). If I move the base idle screw eithr direction it makes NO difference to the engine speed until it is fully screwed in, and even then it's not at idle (I kept a note of where it sat originally and pout it back afterwards).

I am seriously thinking of a complete plenum/sensors/linkage from a breakers now as I am sure it's all been FUBAR'd now!