Saturday, April 26, 2014 - 09:38 pm, by: John Stafford(Johng12)
My 31 takes 3 goes to get it started and when it starts it sounds as if it is only on some of the cylinders. It rights itself within a couple of revolutions, a few seconds. Anyone had this problem? What is involved in checking the injectors? Do I have to take them off and have them professionally done? Can I check their electrical operation without taking them off? Cheers and thanks for any advise.
Sunday, April 27, 2014 - 10:42 pm, by: John Stafford(Johng12)
Yes Jamie, and the leads and everything else that I can think of, this is the old problem that I have been working on for ages (I have been away overseas for a while and now back I am trying to get to the bottom of this problem). I thought that I had it beat with making a new loom for the LPG but in the end that did not solve the problem. I think I will pull the injectors out and get them checked and cleaned and see if that clears the miss on petrol. I am thinking that maybe if one of the injector's solenoids is malfunctioning that it might cause a problem with the message that the ECU is picking up and so compromise the signal to the LPG injectors?
the miss is not a stutter but a dying of the motor like it suddenly dials out a heap of advance, that is why one of the things that I did was change the knock sensors. It dies, picks up and then dies again, repeating again and again when full throttle is applied.
I once had a Magna that died under heavy throttle like this when the injectors were blocked.
If you don't go full throttle you can think that the problem is gone.
I don't usually keep much petrol in the tank (about 1/4 tank) but just put in about 40 ltrs just to make sure that that wasn't the problem: still does the same thing.
Peter Nitschke Junk Filterer South Australia UZZ30 UZZ31
Monday, April 28, 2014 - 07:09 am, by: John Stafford(Johng12)
Peter, if it was the idle control valve wouldn't it be a problem other times too, not just on a cold start. Would there not be a problem when changing from drive to neutral. It seems like only some of the cylinders are firing properly when first started rather than just an erratic idle? The valve is clean by the way, I have had it out previously.
Peter Nitschke Junk Filterer South Australia UZZ30 UZZ31
Sunday, May 04, 2014 - 02:51 pm, by: John Stafford(Johng12)
Hi Mark, Tell me more about the symptoms of the fuel pump ecu? What is the test and what exact difference could it make to things? Could its signal affect the signal going to the main ecu that then sends a message to the LPG ecu?
I just had the injector solenoids checked (all 13.5 ohms) and the injectors cleaned, spray pattern was all over the place, so that now fixed and much better acceleration on Petrol than before but still a dying at times on full throttle.
I plan to take the IAT out tomorrow and check it again as the start up problem is still the same with it taking 3 goes then rough starting, which corrects itself within a few seconds.
I am very interested to hear if the fuel pump ecu will have any effect on the signal getting to the LPG injectors????
Sunday, May 04, 2014 - 06:09 pm, by: Mark Donovan(Mark_donovan)
Hi John - I mention the fuel pump ECU because I once had a similar sounding problem where the engine would fail to start when it was warm. It would eventually start after minutes of trying. Cold starts were no problem.
I believe the way to test it is to bridge two terminals in the diagnostic port under the bonnet. There are instructions here in the V8 section. I would think there was a signal between it and the main ECU, but I can't comment on the LPG ECU as I have no experience with them.
I think with more targeted reading of fuel pump ECU problems in this forum, you may have a better idea of if that's where the problem lies. With two Soarers, you're lucky not to have come across this problem before!
The mention of the spark plug leads because I had once had a problem where it wouldn't accelerate over 40-50km/h and there was just no power. Eventually pinned it down to damaged leads.
Sunday, May 04, 2014 - 10:37 pm, by: Tom Richards(Tomr)
i believe the fuel pump ecu only changes the voltage from ~8v to 12v at the fuel pump. just cruising 8v, start up and hard accelleration 12v. i do not know what the inputs are.
John Stafford DieHard Qld. Soarer UZZ31 GT-L V8 and a UZZ32 # 514
Sunday, May 04, 2014 - 11:28 pm, by: John Stafford(Johng12)
Tom, if that is the case then it sounds as if there may be something there for me with regards to full throttle dying??. If it draws the extra volts then that may be an answer to my 31. I will research some more. Thanks.
Monday, May 05, 2014 - 02:07 pm, by: John Stafford(Johng12)
The IAT was spotless and bearings tight, I thought I remembered that from last time I took it out.
I put the short across FP and B+ and it started with a vengence. The engine is warm though so I have to take it for a run and try wide open throttle after lunch. It makes sense that this would be the problem both with starting cold, needs more fuel, and when really wanting the most out of the engine on full throttle, as on WOT it would need the extra fuel that the 12 volt signal would give.
I am anticipating the link between the fuel ECU and the LPG ecu signal connection, to co jointly correct the LPG miss on full throttle, hope so anyway, will let you know the outcome
John Stafford DieHard Qld. Soarer UZZ31 GT-L V8 and a UZZ32 # 514
Sunday, May 11, 2014 - 04:14 pm, by: John Stafford(Johng12)
Starting problem turned out to be faulty connection of the air flow meter that was fixed with CRC Electrical cleaner. Who would have thought it after my trying another Carmen Vortex unit, never imagined it was the connection, which looked and felt fine.
The dying on both LPG and petrol were different issues: 1. the Petrol injectors had a very bad spray pattern and were not dosing the required amount of petrol at WOT. Once professionally cleaned the car ran great on Petrol. 2. The wiring loom on the LPG had failed insulation in many places and so my son in law and I made a whole new loom and redid all the connections, all done with very high quality wire and attention to detail. In the process we found the number 1 and number 3 wires were not as the wiring diagram for the LPG. We swapped them but there was no real difference noted so thought that they must be right after all and so we left them how they came off. The changeover from petrol to LPG was not noticeably different, but because the petrol injectors were not running how they should have I could not pick up the fault on idle.
Now with the injectors clean and a little more knowledge of reading the laptop tuning program for the LPG I could test to see if each of the LPG injectors are working like desired on the changeover from Petrol to LPG. I noted that the car was stumbling when I changed over #1 and #3 cylinder. I did each cylinder individually!!!! Number 1 and number 3 were around the wrong way. Once I swapped them and took it for a run it was a new car, fast and smooth. Hey how sweet!!!
I have a little tuning fix up to fiddle with from 2 to 3ooo rev range but no big deal. I have my car back again after a year and the replacement of every sensor, bar the crank angle and cam angle sensors, which tested out perfectly.
Cheers all. I will post this to my old threads to make them complete too. thanks for any help that you have given.
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