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 Post subject: No injector pulse randomly at start up
PostPosted: Sun May 12, 2019 4:32 am 
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Joined: Fri Oct 10, 2014 4:53 am
Posts: 132
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Someone might be able to help me.. Swift gti

I replaced tps, maf, water temp sensor for ECU, ECU, injectors tested, fuel pump, distributor and complete assembly of the coil pack, changed grounds and basically everything that came to my mind that could cause this

The problem is no injector pulse, but it doesnt happen all the times, but when it does, is only on start up, after the car starts, there is the pulse everytime and the car runs perfectly fine.

The problem is more common on the second start up, for ex: crank for the first time in 10min without driving, starts up in a second, turn it off right away, and if i try to start it again, there is no more pulse. I have a 12v directly to the injectors, click the button once, fuel gets injected and car starts right away with that method.

The car also starts perfectly all the times if i push it down the road and release the clutch.

Anyone ever had the same problem?


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 Post subject: Re: No injector pulse randomly at start up
PostPosted: Sun May 12, 2019 7:47 am 
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Location: Bunya QLD 4055
I would be looking at the CAS or the earths to the motor.

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If "X" is an Unknown quantity, and a Spurt is a drip under pressure, then an "EXPERT" is an "Unknown Drip Under Pressure".
Why dont they just call it "Womenapause" instead.


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 Post subject: Re: No injector pulse randomly at start up
PostPosted: Sun May 12, 2019 8:10 am 
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You mean Cam Angle Sensor? the one on the distributor? I changed the distributor from a perfectly running gti and it made no difference, i was thinking it could also be the wiring to the ecu or from the ecu to injectors, but the car after starting runs without a problem for as long as you want


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 Post subject: Re: No injector pulse randomly at start up
PostPosted: Sun May 12, 2019 9:26 am 
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Joined: Mon Dec 19, 2016 10:40 am
Posts: 956
Location: NZ
Are your wires in the engine bay hard and cracked especially around the engine? I kept nursing the loom along but when I went to the new link ECU I rewired the entire car. If you have done everything else maybe you have wiring issues


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 Post subject: Re: No injector pulse randomly at start up
PostPosted: Sun May 12, 2019 9:46 am 
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Joined: Mon Aug 25, 2003 12:00 am
Posts: 1622
Location: Londoninium
Battery and starter motor? Is it slow to crank. Perhaps not reaching the minimum rpm for ecu to recognise it turning, and not ordering action.
GTP


Last edited by gtpswift on Sun May 12, 2019 12:46 pm, edited 1 time in total.

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 Post subject: Re: No injector pulse randomly at start up
PostPosted: Sun May 12, 2019 10:31 am 
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Joined: Fri Oct 10, 2014 4:53 am
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Thanks for answering
There isnt much more to it so it might be the loom as swift12 said, but wouldnt that make the problem happen with the car started too? Because the pulsing problems happen at cranking, after its running it runs fine

To my hears it cranks quite fast actually, i have seen low battery starts on gti and even then they seem to start ok

Weirdest problem i have seen through the years to happen to this car..


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 Post subject: Re: No injector pulse randomly at start up
PostPosted: Sun May 12, 2019 11:58 am 
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Joined: Mon Dec 19, 2016 10:40 am
Posts: 956
Location: NZ
I used to be a mechanic...electrics certainly not my forte but I have seen a lot of weird stuff with electrics especially dicky contacts and broken wires. Most of my wires around the engine on my 1989 gti were very brittle and they tended to break a lot...I was having issues with the WTS and replaced the plug and sender....still the same issue until I cut that wire back about 400 mm to the less brittle part and it fixed the issue. When you say no pulse you are checking wether there is power off and on to the injectors at one of the injectors?
If there is a broken wire somewhere often they are fine when cold but not when warm...but no hesitation when it is running when warm?
Any codes?


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 Post subject: Re: No injector pulse randomly at start up
PostPosted: Sun May 12, 2019 12:56 pm 
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Posts: 132
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Yeah, i have dealt with some of those wires.. specially the ones near the water sensors..

The car has a fuel pressure gauge, and after pushing fuel (ignition, before cranking) it stays almost at 4 bar, and when cranking it remains there at 4bar, i also tested with the fuel rail off and absolutely no fuel came through any injector, only then i noticed there was no pulse at the injectors at random times

The car runs like new honestly after starting, even today i did like 70miles and the car ran perfectly, is just at cranking as weird as it looks


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 Post subject: Re: No injector pulse randomly at start up
PostPosted: Thu Jun 06, 2019 8:33 am 
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Up [-o<

Ps: Don't forget, after the car is started, the pulse is there and is absolutely fine, just at startup sometimes


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 Post subject: Re: No injector pulse randomly at start up
PostPosted: Fri Jun 07, 2019 8:50 pm 
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Location: Napier
Im gonna go for a wire that is common to the injectors that while the injectors are shaking during startup, is not making contact.

Happy hunting.

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 Post subject: Re: No injector pulse randomly at start up
PostPosted: Fri Jun 07, 2019 10:28 pm 
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Joined: Sat Aug 22, 2015 4:01 pm
Posts: 129
Location: Australia WA
Try push starting it to see if it starts first go, as starter cranking my be causing massive current draw and loose ground or wiring. Give you an idea where to start looking.

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GTI CAPPO


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 Post subject: Re: No injector pulse randomly at start up
PostPosted: Sat Jun 08, 2019 10:50 am 
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Posts: 132
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Hey, someone just advised me to exchange the FI relay, the one next to the fuel pump, so i might do that this weekend and then give feedback
If that's not the reason, i will be changing all the wiring

About push starting it, the car starts just fine

I give feedback later, thanks


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 Post subject: Re: No injector pulse randomly at start up
PostPosted: Sun Jun 09, 2019 1:08 pm 
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Location: Napier
Thats extreme, changing all the wiring and a bigger job than you think. Intermittent issues are painful to troubleshoot, but I feel like you are missing something. I seriously think you have a loose connection somewhere, or as mentioned, a massive current draw that is dropping the voltage so the ECU or relay is not working.

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A Kiwi learning to fly in a Mk1.


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 Post subject: Re: No injector pulse randomly at start up
PostPosted: Thu Jul 30, 2020 6:26 am 
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Joined: Fri Feb 28, 2014 12:11 am
Posts: 86
Location: Aruba
I know it's a dead thread, but after searching I have the same problem. With the fuel rail disconnected from the engine, and a friend holding the injectors in place nto the rail, no fuel will come out of the injectors while cranking.
Have you found the problem?

_________________
1991-GTi: JE 75mm 11:1 pistons,Ported head, Single UD pulley,Sandros chip,Aluminium flywheel,3tech 222/365 cams, Cultus headers,Cultus IM,50mm tb,Crane cams adjustable cam gears,Apex suspension, 4.39fd GB.
1989-GTi.
2001-Altezza AS200.-sold
2003-EVO7 GT-A


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 Post subject: Re: No injector pulse randomly at start up
PostPosted: Thu Jul 30, 2020 8:26 pm 
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Joined: Fri Sep 03, 2010 10:41 am
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Location: Bunya QLD 4055
3 bar is the nominal factory pressure. Check the ECU chassis is earthed and that the earth strap to the Dizzy mount is connected.

_________________
If "X" is an Unknown quantity, and a Spurt is a drip under pressure, then an "EXPERT" is an "Unknown Drip Under Pressure".
Why dont they just call it "Womenapause" instead.


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 Post subject: Re: No injector pulse randomly at start up
PostPosted: Fri Jul 31, 2020 12:30 pm 
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Joined: Fri Feb 28, 2014 12:11 am
Posts: 86
Location: Aruba
ECU is tightened to the 3 tabs under the dash. I assume it's earthed this way?
The dizzy on top is earthed to the firewall. I'm going to change this wire tomorrow.

Today I measured the voltage / continuity at the C ecu plug (injectors) as per shop manual. All is good. In fact I measured all ecu plugs per shop manual, and everything seems good.

I also cleaned the maf sensor (it was a bit dirty) and after that I measured the maf sensor with a multimeter per shop manual, it's good.
I changed the dizzy with a working one, still nothing.
I measured the coolant temp sensor (blue plug), it's within specs.
Fuel pump is brand new (walbro).

A little backstory on the situation;
My 91 gti has been sitting for almost 4 years because I daily drive my EVO. The body of this mk2 is very rusted. I managed to buy an mk3 shell ('96) last year which is in very good condition. So I took the engine and gearbox out of the '91 and installed it in the mk3. I spent a lot of hours on a mk3 ECU loom double checking for bad wires, plug etc. I basicly stripped it and repaired it.
The weird thing is, after everything was installed to start the engine, I turn the ignition switch on and cranked the engine, engine pretty much fired right up and idled rock steady at 1000rpm. After all these years of just sitting there in my mk2.
I let it idle for about 2 minutes and than tried to slowly raise engine rpm, the engine wasn't rev happy. I tried raising the rpm a bit faster and it just kind of bogged down. It will rev if you open up the throttle body slowly, but it just wasn't rev happy.
Anyway I turn the ignition switch to off after about 3 minutes.

I was happy because it started. After a few hours of talking with a friend that visited me, i just wanted to start the engine back up, and it just didn't want to start back up. I changed nothing on the car / engine / ecu harnass. It just won't start anymore. I'm dumbfounded as of what the hell is going on.

Could the injectors be on their way out after sitting for so long? The mk3 injectors measures 2.9ohms (which is out of spec), but so does the 8 spare mk3 injectors I have.
I have 8 spare mk2 injectors and they all measure 2.4ohms.

Anyway, the injectors just won't fire anymore.

Tomorrow I'll measure the main relay, speed sensor at the back of the cluster and tps cause I don't know what else to measure.

I even clamped shut the fuel return line near the fuel rail. Nothing.

Is it possible there is a problem in the ignition switch?

Oh I also checked the cam timing; lined up the notch at the crank pulley at 0 on lower cover, piston is at tdc, exhaust cam lined up perfectly with marking on valve cover, but the intake cam gear seems like slightly off. The marking on the intake cam gear doesn't line up as nicely as the exhaust. Exhaust is perfect, but intake is just like a "hair" off. I'm not sure if that is ok.

I'm just out of ideas what to check.

Any ideas?

Worst case I take out the ecu loom and recheck everything again. Open it up full to see each wire.

_________________
1991-GTi: JE 75mm 11:1 pistons,Ported head, Single UD pulley,Sandros chip,Aluminium flywheel,3tech 222/365 cams, Cultus headers,Cultus IM,50mm tb,Crane cams adjustable cam gears,Apex suspension, 4.39fd GB.
1989-GTi.
2001-Altezza AS200.-sold
2003-EVO7 GT-A


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 Post subject: Re: No injector pulse randomly at start up
PostPosted: Fri Jul 31, 2020 3:33 pm 
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Joined: Fri Sep 03, 2010 10:41 am
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Location: Bunya QLD 4055
You could look at the fuel filter or for stale fuel. Dont forget the MK2 and MK3 ECUs and harnesses are different. Is there enough fuel in the car and does the pump prime? Thats it for me!!!

_________________
If "X" is an Unknown quantity, and a Spurt is a drip under pressure, then an "EXPERT" is an "Unknown Drip Under Pressure".
Why dont they just call it "Womenapause" instead.


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 Post subject: Re: No injector pulse randomly at start up
PostPosted: Mon Aug 03, 2020 8:19 am 
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Joined: Fri Feb 28, 2014 12:11 am
Posts: 86
Location: Aruba
pictureshowman wrote:
You could look at the fuel filter or for stale fuel. Dont forget the MK2 and MK3 ECUs and harnesses are different. Is there enough fuel in the car and does the pump prime? Thats it for me!!!


pictureshowman wrote:
You could look at the fuel filter or for stale fuel. Dont forget the MK2 and MK3 ECUs and harnesses are different. Is there enough fuel in the car and does the pump prime? Thats it for me!!!


Tank is clean, fuel is new. Fuel filter is new. Ecu harnass is mk3. Gti shell is mk3. Fuel is almost half tank. Fuel pump does prime as per workshop manual

Yesterday I took out the ecu harness. I dismantled it completely. Check every wire. Measured every wire to their ecu plug pins. I did replace yesterday the maf sensor plug and a length of its wire as the old one was "pretty". Did the same thing for the wire that goes to the injector harnass. Put everything back together and into the car. Still nothing. Fuel pump primes. Injectors doesn't want to fire. I'm 99.9% sure it's not the ecu harnass. I also check every chassis ground, cleaned them up, bought new battery terminals, put some extra grounds on the igniter (to firewall) and also at the back of the engine to battery ground.

Tomorow I'll check the injector harnass, another maf sensor, another fuse box (under dash), main fuse wires and another ecu.

Engine does have spark. I spray a little carb cleaner in the intake manifold and it wants to start, but nothing.

_________________
1991-GTi: JE 75mm 11:1 pistons,Ported head, Single UD pulley,Sandros chip,Aluminium flywheel,3tech 222/365 cams, Cultus headers,Cultus IM,50mm tb,Crane cams adjustable cam gears,Apex suspension, 4.39fd GB.
1989-GTi.
2001-Altezza AS200.-sold
2003-EVO7 GT-A


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 Post subject: Re: No injector pulse randomly at start up
PostPosted: Mon Aug 03, 2020 10:55 am 
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Joined: Fri Feb 28, 2014 12:11 am
Posts: 86
Location: Aruba
Ok....SOLVED!

After my last post a few hours ago I searched some more.

Got to the point I changed the MAF sensor and coolant temp sensor. That did the job.

Idled strong. Engine strong. Revs very agressive.

Thank you.

_________________
1991-GTi: JE 75mm 11:1 pistons,Ported head, Single UD pulley,Sandros chip,Aluminium flywheel,3tech 222/365 cams, Cultus headers,Cultus IM,50mm tb,Crane cams adjustable cam gears,Apex suspension, 4.39fd GB.
1989-GTi.
2001-Altezza AS200.-sold
2003-EVO7 GT-A


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