Wannabe Tuna

Holden/Delco Tuning. ALDL, OBD 1.5. Circa 1989 to 2004.
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Gareth
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Joined: Fri Mar 14, 2014 8:37 pm
Location: Bacchus Marsh, Vic

Re: Wannabe Tuna

Post by Gareth »

Are you sure that the LPG mixer isn't causing your restriction?

I'd piss it off if you're not going to be running LPG...
According to chemistry, alcohol is a solution...
Maxxx
Posts: 62
Joined: Wed Feb 19, 2014 5:55 pm
cars: VS Commodore ute and a VY Commodore ute
Location: Mornington Peninsula Vic.

Re: Wannabe Tuna

Post by Maxxx »

Hi Gareth
I had the hole LPG assembly off the car from the MAF to the TB and replaced it with a new factory style plastic tube. That's when it ran the worst, with the tube on it the frequency runs around 3300 at idle. I put the mixer and old tubing on the car to see where the frequency would be. It came down to 2700, so I put the petcock in the rubber elbow to see if I could use that to lower the frequency down to the 2400 area by inducing a vacuum leak. I am able to get the frequency there but I know it's not the proper fix. What it has done is stop the idle surging I was having. I drove the car to work today and logged it. I will look over the log when I get home. Thank you for the response.
immortality
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Joined: Thu Apr 09, 2009 12:31 pm
cars: VH, VN, VS, VX

Re: Wannabe Tuna

Post by immortality »

Maybe the tune has been fucked with?

Have you pulled the cover off the PCM and had a look at the memcal?
Maxxx
Posts: 62
Joined: Wed Feb 19, 2014 5:55 pm
cars: VS Commodore ute and a VY Commodore ute
Location: Mornington Peninsula Vic.

Re: Wannabe Tuna

Post by Maxxx »

Hi immortality
I have pulled the cover off the PCM and looked at what I thought was the memecal(the blue chip) but there was no sticker on it. I haven't tried to pull it out of the PCM and see if the blue cover comes off.
immortality
Posts: 3416
Joined: Thu Apr 09, 2009 12:31 pm
cars: VH, VN, VS, VX

Re: Wannabe Tuna

Post by immortality »

Correct, the blue chip cover is the memcal. If it's original and hasn't been tampered with it will have a silver sticker over the little window with a 4 letter and 4 digit code. If it's been removed you can generally tell by he condition of the little sticker.
Maxxx
Posts: 62
Joined: Wed Feb 19, 2014 5:55 pm
cars: VS Commodore ute and a VY Commodore ute
Location: Mornington Peninsula Vic.

Re: Wannabe Tuna

Post by Maxxx »

Well I've had a chance to look at the memcals, neither one had a sticker on the blue cover. I pulled the covers off and the there are stickers on the memcals
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immortality
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Joined: Thu Apr 09, 2009 12:31 pm
cars: VH, VN, VS, VX

Re: Wannabe Tuna

Post by immortality »

That doesn't look like it's been tampered with.
Maxxx
Posts: 62
Joined: Wed Feb 19, 2014 5:55 pm
cars: VS Commodore ute and a VY Commodore ute
Location: Mornington Peninsula Vic.

Re: Wannabe Tuna

Post by Maxxx »

Well that's good to hear. That one is not the original PCM from the car, it's one I had laying around and put it in the car to see if it ran differently. I didn't notice any real change. So the over fuelling issue started around the time I pulled the LPG system off the car and replaced it with a standard intake pipe. I still don't know if the tune was changed when the LPG was added. I say this because the mixer is a restriction I can fell when I accelerate. The cars struggles to get past 4000 rpm, with the new tube and no mixer it easily and quickly will rev past 5000. I wonder if the tune was changed to use the slower air speed caused by the restriction of the mixer. With the new pipe and no mixer the MAF frequencies are higher at idle and 2000 than they should be which makes me think the PCM is adding fuel according to the frequency which is higher than actually air speed. Dunno
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Gareth
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Re: Wannabe Tuna

Post by Gareth »

What is your coolant temp sensor reporting?
According to chemistry, alcohol is a solution...
immortality
Posts: 3416
Joined: Thu Apr 09, 2009 12:31 pm
cars: VH, VN, VS, VX

Re: Wannabe Tuna

Post by immortality »

That doesn't make sense though, the MAF measures airflow, 2 different MAF's, the same frequency numbers, 2 different PCM's the same number same result. Something is throwing off the MAF reading, the PCM/tune are only doing what is programmed and adding the correct amount of fuel to suit the high MAF reading resulting in the rich AFR condition. We know that a stock MAF with the stock intake pipe should give the correct number but instead it reads high so we need to figure out why. It's almost like they have tricked the MAF somehow to compensate for the restriction of the LPG shit.

Have a look over the wiring loom and see if it's been modified. Check alternator output, check the MAF output voltage at the PCM and compare at the MAF plug. Check for resistance in the signal wire from the MAF to the PCM.
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