Disco Stalling when in Motion
So, I have a 95 V8i, auto. Since purchasing a little over 2 years ago, it has had on-going idling or ignition issues. Sorry, this is a long one, but the intermittant issue has been going on for quite a while now.
It is dual fuel. Finally, the old venturi system was replaced with a vapour injection set-up. The new lpg set-up definately is more powerful and there is now no real difference between petrol and lpg as far as grunt goes. Prior to this change, numerous sets of leads and plugs were replaced and even one of Bee Utey's BIM024 set-ups. (Bee Utey's set up was a great improvement at the time).
Every time something is changed, the idle was either un-changed or improved for a short period of time. Funnily enough, prior to the new lpg system, the idle on lpg was better than petrol. The vapour injection system had the opposite affect. Petrol idled significantly better than lpg. But both had idling issues.
Finally, I decided to replace the distributor with a Scorcher set-up. Bee Utey's set-up was with a Bosch MEC723 coil. Scorcher bloke said that would work fine with new distributor. New distributor set-up at 9BTDC (should probably be 10BTDC) with Bee Utey's second hand coil, still idling terrible.
Changed the coil to Scorcher's recomended Bosch MEC717....no difference. As I did this, I noticed what sounded like a sucking of air. Originally, thought that it was from the snorkel. But wth further investigation, discovered that the IACV was leaking.
Replaced IACV and with the new leads, coil, temperature sensor, potentiometer and distributor. I received one perfect week of starting, idling and running until yesterday. I felt pretty good as everyhting was running so good.
Now onto yesterday. New tank of lpg in the morning. Pretty hot in Brisbane yesterday but nothing compared to down South. Moving through traffic on the run home, probably doing between 30 and 40 kph. Stalled, smoke from under the bonnet, rolled to kerb, popped bonnet to see oily residue as if sprayed on passenger side chassis rail, lpg convertor and bit on the exhaust (hence the smoke). Switched to petrol, drove home fine.
This morning, kept it on petrol and drove to office ok, idle had increased when parking. Adjusted base idle down a tad, seemed ok. Saw my lpg installer and asked about residue, answer that it should or could not be from lpg system?
So, switched back to lpg, drove around for awhile, seemed ok. Drove home a bit earlier today on lpg without much traffic. Car stalled whilst cruising in suburban street (slightly up hill, probably in 3rd, 50kph). Thought it must be lpg issue. Re-started on petrol and continued driving on petrol....school run.
Coming home, just hit crest of a long steep hill, about 60kph, 3rd or 4th. Same stall, this time on petrol.
Now, I have no ideas left. It has never stalled or missed before with accelerator.
So in a nut shell ....
Regardless of whether it runs on petrol or Gas .... the motor cuts out while driving
So this eliminates ..... Fuel pump
Your changing of parts eliminates ....
Dizzy
Spark module
TPS
But it is obvious for electrical rather than mechanical .... The "No run on Gas" gives this away
Check the wiring harness and follow the path of where the gas installer spliced in his lines
Check all earth straps & earth points
Thanks, will do tomorrow and post results.
Originally Posted by mike 90 RR
Just to elaborate a little further .....
The switch that you press from petrol to gas on ya dashboard .... If the switch finds a "neutral" point ... then it will cut out petrol and gas .... hence no fuel
Im not saying that the switch is suspect ... but follow that line of thought and follow the wires
Perhaps Bee utey could expand, if need be
Your erratic idle issues is a different matter ... I can comment on things to do, later on
After thought Wildcard .... Any chance you can borrow a MAF to use for a while
AT REST
OK gas injection will cut out regardless of failure of the ignition or the petrol ECU as the gas ECU reads the petrol one. So primo number one would be to check the tightness of the wire that connects the petrol ECU to the NEGATIVE side of the coil. Remove, clean, check, tighten. Also check the resistor thingy in the wire to the ECU, it is usually taped up to the loom.
Now to check if the ignition is dying (which will kill everything) use a safety cut-out, like the type used with the old gas system. Wire it on the dash somehere so you can see the little light on it, that is with earth, coil pulse and positive wires connected. The coil pulse can be derived from the coil lead, wrap a wire 6-7 times around the coil lead, tape it up and run it to the safety cut-out pulse connection. Now next time it dies watch the light on the safety cut-out. If the light stays on you still have ignition functioning. Therefore the fault will be with the petrol ECU stopping. If you had kept the simpler gas system you wouldn't need the petrol ecu to function, now you do. Bad luck, I prefer the KISS principle myself.
AT REST
Sadly he's now got gas injection, the switch is just a momentary push button or simple rocker switch, the gas ECU handles all the changeover by programming.
Thanks Mike and Bee Utey
I'm basically a rev head at heart and the change to injection allowed comparable gas v petrol performance. Having said that, I have been told that a good lpd installer can get similar results from the old style system. Unfortunately, not so in my case....then again, maybe I didn't find a good installer.
Having checked the loom today, the wiring to the left bank of the lpg injectors have symptoms of over-heating. Maybe this is from the extractors, but the wiring is a good 250-300mm away. Some of the wires were virtually down to bare wiring. I have taped the up for a quick-fix temporary solution. The next wire to check is the ecu to negative coil.
I will post further. Thanks again.
Sorted, Maybe?
Quick update.
Monday: I had the lpg installers check their wiring to make sure it was not the problem. They assure me that it their stuff is ok. However, still signs of stalling issue.
Tuesday: Dropped it into a local dyno tuning and performance mechanic before heading up to Townsville for a few days of work. Picked it up a couple of hours ago.
Diagnosis: After many hours of testing on the dyno and the road with the most of the focus on the ignition, mechanic reckons he has sourced the issue to a drop out in the wiring loom to the coil. The coil is getting intermittant power drop. Said that is probably a relay or sender unit in the dash somewhere or a break somewhere in the loom.
Solution: Rather than spending more of my money trying to find exactly what or where that is occuring, he has wired the power to the coil directly via a relay. This appears to have also sorted out the remaining slight fluctuation in the idle also.
Time will tell, but hopefully this is finally it.
ChatterBox
I'm basically a rev head at heart and the change to injection allowed comparable gas v petrol performance. Having said that, I have been told that a good lpd installer can get similar results from the old style system. Unfortunately, not so in my case....then again, maybe I didn't find a good installer.
Unfortunately you are in Brisbane, Bee Utey is brilliant with gas instals, diagnosis, tuning etc but in Adelaide
Yeah, Bee Utey certainly does seem to know his stuff.
I have now moved the ignition module from the side of the scorcher dissy back to Bee Utey's remotely located bracket that he made up for me to minimise the risk of heat failure.
The old D1 seems to behaving itself ignition wise at the moment. The power steering box and central locking is another story.
Posting Permissions
| Search AULRO.com ONLY! |
Search All the Web! |
|---|
|
|
|
Reply With Quote
Bookmarks