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3.9 non runner


kentranger

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strangly enough i have had to play with the timeing to get it drivable. seems to be a good spark at the plugs but the ignition timeing needs to be about 25 btdc or the car wont pull away it is very weird and that is either gas or petrol. i think as i said earlier i need to get it tuned for mixture possibly then timeing and see if it makes any difference.

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strangly enough i have had to play with the timeing to get it drivable. seems to be a good spark at the plugs but the ignition timeing needs to be about 25 btdc or the car wont pull away it is very weird and that is either gas or petrol. i think as i said earlier i need to get it tuned for mixture possibly then timeing and see if it makes any difference.

That's way, way too advanced. Book figure for petrol is 6BTDC at idle, I used to run 12BTDC for LPG/petrol - that was lumpy at idle on both, but gave reasonable performance on LPG.

Stupid question I know, but you're definitely taking your timing signal from the cylinder 1 HT lead? I take it you're measuring timing with a timing light?

If it's the same on LPG and petrol you can rule out a fuelling issue. In any case the hotwire ECU is self tuning, so far as I'm aware - just unplug the battery for a while to reset it then reconnect and go for a drive of at least five or six miles on petrol (don't turn the LPG on) to course tune it.

Can't remember what type of LPG kit you have, but I've just thought of a couple of things that might affect fuelling on both systems. If you have an injection type LPG kit, many (all?) of them monitor the injector switching from the petrol system and use it to set LPG fuelling, so if petrol is off, LPG will be too. Also, unless you have an open loop LPG kit (unlikely on an EFI car), both systems will be thrown if a lambda sensor is disconnected or faulty - check they're securely in place and the wiring is okay.

Anyone got any other suggestions.

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i am taking the timeing light from the lead on the right hand bank looking from the front of the engine back. its the first lead on the right hand side. i also remembered reading on the forum about the tdc marks on the pully wheel being out so i checked it when the head was off and it seems to be spot on. the lpg system i have is voltron. not sure what type it is how would i tell. i had set the timeing at 8 btdc and it seem to idle slightly better but as soon as i put it into gear it just died. no stutter or anything just stop dead.

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i am taking the timeing light from the lead on the right hand bank looking from the front of the engine back. its the first lead on the right hand side. i also remembered reading on the forum about the tdc marks on the pully wheel being out so i checked it when the head was off and it seems to be spot on. the lpg system i have is voltron. not sure what type it is how would i tell. i had set the timeing at 8 btdc and it seem to idle slightly better but as soon as i put it into gear it just died. no stutter or anything just stop dead.

If you have a second set of fuel injectors for the LPG it's an injected type. If you have a pipe going to ring on the air intake just before the throttle you have the older venturi type system.

You're doing the timing right.

I'm afraid I've no idea what would make it behave like that. Hopefully someone will be along in a bit who can shed some more light...

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This is seriously werid.

No V8 should have a tickover timing setting of 20+ degrees.

You need to go back to baiscs.

1. Forget LPG - get it to run right on petriol

2. Have you got GENUINE Leads car rotor arm ?

3. Have tyou had the dizzy out ?...sounds as though the timing is out dizzy wise ?

4. Have you checked the fuel pressure ?

5. What plugs are you running

6. Check the connector on the resisitor pack

7. disconnect the extra injector (the one on the plenum) take off pipe and block

8. check the throttle potentiometer settings is correct also that it moves up smoothly to full throllte

9. check and clean all the engine harness earths

10. What the air filter like

11. Check the hose between the AFM< and plenum is is ok (ie no holes) and tight

12. What have you done to the engibe etc since it ran ok ?

Nige

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3. Have tyou had the dizzy out ?...sounds as though the timing is out dizzy wise ?

I thought that, but surely if kentranger is measuring the actual timing (at the HT lead), that can't be relevent?

7. disconnect the extra injector (the one on the plenum) take off pipe and block

All the 3.9s were hotwire, so no cold start injector - that's a flapper thing. They have a stepper motor that opens and closes a bypass that lets more air in past the throttle - it's on the back of the plenum - instead. Worth taking that out and checks it's clean and working, but I can't see it causing that much of a problem.

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No resistor pack on Hotwire either, get with the times Nige ;)

I would be highly suspicious of the LPG system that sounds like it's spliced into the EFI system, if wires have been tinkered with there's a fair chance one of them will have been done less than perfectly. If you see Bodgelok connectors, consider ripping it out or re-doing it properly as they are a sign of bodgery.

Other checks you can do:

- Listen (or feel) for injectors clicking, if they're not clicking you've got problems further back up the system.

- Stick a clear inline fuel filter in the RETURN line, this is the line that comes out of the fuel pressure regulator. It will allow you to see if fuel is being returned and diagnose either a dead regulator or low pressure (if no fuel comes back) and fuel flow / blocked filter if barely a trickle returns. At idle it should be rushing past. Note that the ECU won't switch on the fuel pump until it thinks the engine is cranking or running.

When I recently had problems with mine, it refused to start, not even a cough, until I put new plugs in and it roared into life immediately so it's worth trying.

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Yeah,

yer both right knackered and I'm gettin me hotwire mixed up with me flapper :D:)

Mind you Mr Fridge I diagnosed yours spot on didn't I :P ??? Ner ner Ner buttons and Ner :P

Ner :P

Anyways

Too much time on both systems , they "Blend" the only common item and problem being Lucarse components :lol:

The rest of me thoughts are i think correct, so check and report back :)

Nige

Not sure of me wire from me flap :rolleyes:

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i am taking the timeing light from the lead on the right hand bank looking from the front of the engine back. its the first lead on the right hand side. i also remembered reading on the forum about the tdc marks on the pully wheel being out so i checked it when the head was off and it seems to be spot on. the lpg system i have is voltron. not sure what type it is how would i tell. i had set the timeing at 8 btdc and it seem to idle slightly better but as soon as i put it into gear it just died. no stutter or anything just stop dead.

You may have fixed the original problem, but ended up with another. When you replaced the rotor arm, is it possible that you pulled a little too hard to get the old one off? Check that the bob weights and springs under the base plate in the dizzy are all still connected correctly and free to move under centrifugal force. Simple check without dissmantling is to remove and block dizzy vac hose, shine stroboscopic timing light at timing marks and rev engine. Timing marks on pulley should move smoothly and return as engine is revved and left to return to idle. Check also that the vac hose is in good condition, and suck on vac hose connected to dizzy with engine idling. You should not be able to suck free air, and you should also be able to see the timing marks move when using the stroboscopic timing light.

Double check for air hose leaks, jammed or gummed up idle stepper valve and plug leads on correct plugs.

Hope this helps,

Regards,

Diff

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hmm just recieved all the replys. now im really confused lol. right firstly the lkpg system is the old venturi type. secondly the injector tops seem to have the proper plugs on them from the controler boxes for the lpg. so there is no dodgy wireing as far as i can see. yes i did pull a little hard on the rotor arm and yes it did all fall apart but i managed to get it all back together again and that side seems to be working fine. im going to test fuel pressure again today. it seems to run sweet about 2500 revs but anything below that its lumpy as hell. i can hear a rumble from the engine when its on idle but im nearly 100% sure its the power steering pump so ill disconnect it later and run it up to see if it has made a difference. i must admit it does run a little more even when on gas. also i read that the fuel pump shouldnt kick in till the engine is cranking?? i can hear the pump kick in as soon as the ignition is on and then it cuts out after about 6 seconds. it has not got genuine cap or arm on it either and have recently heard that this does make a very big difference. so ill get another cap and arm from barrets. do the leads matter is there not genuine?

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it has not got genuine cap or arm on it

From my own experience, get the pattern stuff in the bin and get genuine Lucas (usually cheaper from a Land Rover dealer for some reason)

I noticed you'd repalced hte HT leads, did yo udo them one at a time? Often the dizzy is not aligned correctly, so what you thought was Nº1, wasn't. Don't ask how I know that!

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I'd ignore the fuel pump kicking in, on flapper types it doens't kick in until the flap moves but on Hotwire it may well come on briefly to get up to pressure for a priming pulse before starting, and switch off again after a few seconds if the engine isn't running.

It at least shows the ECU has control of the fuel pump, so the ECU and relay are working OK, you just need to check the pump is pumping OK. If you have a hatch in the boot floor to get to the pump you can cheat and wire the pump directly to a battery sat in the boot, this was how we proved the dodgy earth on mine.

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Fridge is correct

3.9 HWs ssytems prime, you turn ignition on and the system sort of goes Zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz Click !

This means all is well.

The suggestion re if you pull the rotor arm off the springs can pop out of the bob weights is spot on and worth checking - one way is to remove cap and get rotor arm and see how much "Slack" you have turning both clockwise and anti clockwise, should be very little, bigish movement = spring off.

If a spring is off then you will not get ignition advance and as such you would ned to advance it a lot to "Compensate", so good call.

also, check the fuekl pressure, it should be 30 psi +/- a couiple of PSI, less than 24 and its not enough to power engine.

BIN rotor arm dizzy cap and leads, fit genuine stuff, PERIOD !

I have loast track of how many time pattern **** has caused problems, INC the king lead from the coil

Nige

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Hi,

Im new to the forum so - Hello....

Ive had similar issues with my 3.5EFI, which were initialy cured with wd40 under the rotor arm to free it up. It was extremely stiff, and the engine wouldnt run below 2500rpm. After that it was "free", but you can still feel the relatively light resistance of the bobs and springs. (clockwise only!)

I dont think its a complete fix - as the engine feels a little gutless, so I reckon the advance isnt working as well as it should. When testing the advance, what difference do you look for regarding vacuum connected versus disconnected? How many degrees of advance should a "good" dizzy give?

yojimbo

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ight i have started again lol. firstly i got it running again with no problems. it just fired up after as couple of turns. it was idleing a little high so i turned it down to just under 1000 or what seemed to be about that speed from the rev counter. altough it was idleing again very bad i tried to put a timeing light on it.

set the light at 15 to see if i could find the mark and they were no where to be seen. took it up and up and up till i eventually found the mark at 45 - 50. can an engine run at that far out??. i tried unplugging the retard and advanced but that made no difference to it. the timeing light is not a cheepie. i bought it about 4 years ago from mac tools at 110 quid so i know that should be ok. i am completly baffled now. lol i know i am taking the pick up from the number 1 plug but is it possible the timeing is so far out that it is actually fireing 1 piston out?? will it run like that?

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Right.

Remove ECU

Turn engine over till your near TDC

Then shove in gear and rock till TDC EXACTLY

If auto 24mm bolt into pulley and pull to TDC

Remove No 1 spark plug.

Check TDC and also chaeck that you are on compression not exhaust (if desperate remove rocker rotate engine and check both No Valves closed.

When you are AT ATC and ON Compression stroke, run from PLUG no 1 back to dissy.

Mark with pen the dizzy base that lines up with no plug traced back to dizzy cap, and then remove dizzy cap.

The rotor arm should be EXACTLY where the mark is.

Bet it isn't !

Report back, we will sort this !

Nige

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As I have found in the past, the V8 will run (albeit very rough) on pretty much ANY timing, we were twisting my dizzy as far round as it would go in both directions and the engine was still chugging and spluttering! We were both saying "Why won't the bl**dy thing stall?" :lol:

As Nige says, you can't trust the timing marks on the crank pulley. Real Steel sell a "timing tape" that sticks onto the pulley, so once you find TDC you can stick it on and KNOW it's right, I will be doing this when I build my engine up.

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