I am really fooked now, urgent help please (and its not a p38!)

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fett

fett

Well-Known Member
Posts
8,637
Location
South Hampshire
Ok so taday I had two jobs to do, fit new leads and coil to reslove leads light show and also to adjust the idle speed which was at 450rpm, should be 750-800rpm I gather. BTW this is for a 1990 3.9 classic with hotwire.

So fit coil, it runs great for test drive-shop-bank etc all good.

Come home, after reading up on here about idle speed adjuster on inlet manifold/throttle body not AFM.

So adjust it a little, nothing happens, try other way nothing happens, so get more exteme with adjustments nothing happens (revving between adjustments)exept the closer I get to fully anticlockwise there is a wooping sound,gets louder when engine is revved. I didnt like the sound of that so I just put it back slightly more anticlockwise than it was originally it idled at the same speed and ran ok, went for a drive all good , parked for an hour and then restarted it revved a little higher then after a while stalled, stalled 3 times on drive home, ran ok under lead but stalled at idle.

tried to have a play on the drive in the dark but the exhaust stank (rich I think) and you could hear a little missing from the tail pipe and I couldnt get it to run right without the above or it dying completly or all three mostly.

I thought this was purely an idle adjustment screw, I have not touched the one on the AFM to avoid exactly this problem!:doh::doh:

Please help if you know what to do to sort this, I dont have an analyser and the haynes book doesnt help for the hotwire system.
 
long time since I played with a 3.5i or 3.9I but if you can get screw back as near as possible and have not played with air flow meter.
The throttle pot position from memory causes agro if not set correctly black 3 wires 2 screws.
 
fett said:
Must be to do with me feckin with the adjuster screw though, I am sure
Click to expand...

Fett, I not sure what screw you're talking about, is it on the throttle levers or is it in the throttle body?

Could just need to clear the memory. Pull positive lead from battery for a while, have a cuppa while the cpu reset itself then hook lead up again, may help.
 
Sounds like mine when I changed the leads. Probably not the same problem though.
I know you have checked the leads for routing and what hoave you. My leads wheere well out of order. plus the dizzy was out by a fair way. Ran great before I dd the service though for some strange reason. As it stands I have next weekend free. So I can come donw and beat the crap out of. sorry i mean try and sort oout your RRC. Hopefully mine will be on the road by then. If not I'll be coming down in the other halves 309.
 
ssmn1234 said:
Fett, I not sure what screw you're talking about, is it on the throttle levers or is it in the throttle body?

Could just need to clear the memory. Pull positive lead from battery for a while, have a cuppa while the cpu reset itself then hook lead up again, may help.
Click to expand...

On the body , the one that should have a tamper proof plug, wish it had lol
 
Khryztal said:
Sounds like mine when I changed the leads. Probably not the same problem though.
I know you have checked the leads for routing and what hoave you. My leads wheere well out of order. plus the dizzy was out by a fair way. Ran great before I dd the service though for some strange reason. As it stands I have next weekend free. So I can come donw and beat the crap out of. sorry i mean try and sort oout your RRC. Hopefully mine will be on the road by then. If not I'll be coming down in the other halves 309.
Click to expand...

Yeah it was ok after I did the leads and the coil it was only after I fecked with that screw it went wrong, I have got my BMW specialist coming to have a look at it, reminds him of the technology BMW had when he was an apprentice (he's 36 -shows how behind LR were) I hope he can get it running again at least- it will cost me though!

Yeah come down with yer biggest set of hammers and we can make it in to a P38- it goes wrong often enough. Its the works Christmas do on friday so I will be hung over but I can still use an angle grinder!
 
fett said:
Yeah it was ok after I did the leads and the coil it was only after I fecked with that screw it went wrong, I have got my BMW specialist coming to have a look at it, reminds him of the technology BMW had when he was an apprentice (he's 36 -shows how behind LR were) I hope he can get it running again at least- it will cost me though!

Yeah come down with yer biggest set of hammers and we can make it in to a P38- it goes wrong often enough. Its the works Christmas do on friday so I will be hung over but I can still use an angle grinder!
Click to expand...

OK, he should know.

Get him to drop a new rivet in it while his at it, so you are never tempted again.
 
Fett,

STOP STOP STOP!

If you're messing with the base idle speed you need to disconnect the stepper motor because as you turn the adjuster screw the ECU will be trying to compensate.

Don't worry it is not an unrecoverable situation. I'll get back to you shortly.
 
Well he never showed up , which is annoying as I could have had a go in the daylight!

I will try tomorrow, I have PM you a couple of questions kev, thanks!
 
ok , so I have been out there since 10am,feck its cold!

Got it to run , after following your instruction and changing the plugs as it was so rich they were wet, it was running good but with a bit of a flat spot stratight from idle, it idled at about 500 rpm but doing all the stepper motor stuff didnt work, it stalled without the stepper/with the pipes blanked off untill the screw was about 7 turns out,then it was too rich to run properly. then when we hookd up the pipes again it stayed at about 500rpm anyway.

so we leaned it off again and had it running ok left it idleing for about 10 mins before we checked the emmission (as I was happy to quit whilst I was ahead at this point),just before we were about to it died and would not restart-no spark!

Changed coil, cleaned earth and connections,swapped wires, no spark. 12v coming into coil but nothing coming out.

I forgot to say my number 2 mechanic turned up out of the blue just before I had it running so he has been doing the wires (he also moved the trim screw on the AFM a littlecould that have caused no spark?), he thinks it might be the amplifier,luckily I have another dizzy which has had 2-3 plug conversion job on it so we are swapping the amplifier and conversion wiring over onto mine now to see if that will work but its getting dark and we arunning out ideas-what a sunday!!

Thing is I only had touched the coil and idle scerw nothing else, to much of a conincidence for it to be anything else??

Any help greatly apprecated!!!
 
Last edited:
fett said:
ok , so I have been out there since 10am,feck its cold!

Got it to run , after following your instruction and changing the plugs as it was so rich they were wet, it was running good but with a bit of a flat spot stratight from idle, it idled at about 500 rpm but doing all the stepper motor stuff didnt work, it stalled without the stepper/with the pipes blanked off untill the screw was about 7 turns out,then it was too rich to run properly. then when we hookd up the pipes again it stayed at about 500rpm anyway.

so we leaned it off again and had it running ok left it idleing for about 10 mins before we checked the emmission (as I was happy to quit whilst I was ahead at this point),just before we were about to it died and would not restart-no spark!

Changed coil, cleaned earth and connections,swapped wires, no spark. 12v coming into coil but nothing coming out.

I forgot to say my number 2 mechanic turned up out of the blue just before I had it running so he has been doing the wires (he also moved the trim screw on the AFM a littlecould that have caused no spark?), he thinks it might be the amplifier,luckily I have another dizzy which has had 2-3 plug conversion job on it so we are swapping the amplifier and conversion wiring over onto mine now to see if that will work but its getting dark and we arunning out ideas-what a sunday!!

Thing is I only had touched the coil and idle scerw nothing else, to much of a conincidence for it to be anything else??

Any help greatly apprecated!!!
Click to expand...

I suppose before anything else you need sparks to get the thing to fire. Start with the easy tests first. Do you get a big fat spark off the king lead when engine cranked? If yes, problem is probably the rotor arm; if no then either the coil has died or the ignition amplifier is duff or the pick up air gap is too big. I would go with rotor arm myself but if you have Haynes/Rave or workshop manual, work through the ignition system tests, all you need is a decent digital volt meter.

Once you can get sparks and get the engine running you need to see why it has a flat spot (hesitation I presume) off idle; this is likely to be either ignition timing not spot on or iffy vac advance unit/split or leaking hose to vac advance.
 
BTW if you want to try setting the air flow meter take a digital volt meter and set to measure resistance. Carefully take off the plug on the air flow meter, measure the resistance between the outside pins, you are looking for a reading of 300ohms. You can adjust the reading using the screw (under the tamper proof plug). The air flow meter can be set this way without the engine running or power connected to it so a useful check.

Hopefully that will give you a mixture setting that will not be too rich or too lean.

If the mixture is still too rich then you need to be thinking about the coolant thermistor or possibly the air flow meter is faulty or the ECU is faulty and not reading the air flow meter.

Going back a bit, you said something about changing the coil. Tell me you haven't put a "high performance" coil on it. V8's dont like these, stick to standard spec Lucas/Bosch coils only. Also, make sure all the earth points are clean and making good contact - this is very simple but very important. So, dissassemble, clean and reassemble with vaseline the main battery earth at the chassis. The multiple earth point under the header tank (just behind battery), coil mount, back of engine (RHS goes up to bonnet). Again, use DVM set to audible tone for continuity to check good clean earthing.
 
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