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My Dyno results and SDS issues . . .


Garrett76Zt

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Garrett' date='

 

Nice results there mate. I'm going to have to get mine onto a dyno as soon as I've put a decent transmission under it.

 

WRT your problem, I'm unsure about SDS systems, so lets see if we can't figure out some more stuff:

 

1. When you say backfire do you mean unburnt fuel in the exhaust? Or do you mean a backfire backfire as in through the intake?[/quote']

 

Out of the exhaust . . .

 

2. If you are sitting there and you rev it up and down a few times (to simulate driving) does it die if you back off?

 

No. The hot engine misfire only happens under load and above 2k rpm and only seems to happen after the car has been running awhile.

 

3. Where is the O2 sensor positioned for tuning? (please assure me thats its a wideband O2 sensor)

 

Yes Wideband. Its located about 2 1/2 feet back from turbo.

 

4. Have you hooked up a simple knock sensor to see if its pinging?

 

No knock sensor, Car is definitely safe as far as AFR's go when in boost but i havent yet had this problem while in boost anyways. It happens when i'm cruising above 2k rpm so like 10 inch vacuum or so.

 

5. What AFRs are you tuning for under boost?

 

High 11's

 

 

I need to focus first on why this stupid thing like to die at idle. Could this have anything to do with a screwy turbo timer? Maybe it is cutting ignition while idling or cruising, cause the car will start right back up every time.??

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Could definitely be a turbo-timer, I'm not sure how sophisticated the SDS is but I'd try turning off all the `cuts' in it for the time being, either that or check its error history to see if it will tell you if its cutting anything on purpose.

 

I just read the other thread on your problem, did you follow the advice there about checking decel fuel delivery? Basically it should go to zero. And about heat? Insulated the coils and as much of the other electrics as possible?

 

Dave

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Hi there Garret76T!

 

I had a very similar thing happen to me when I was getting my Z going 4 years ago.

I had a piece of s#*t computer (an Injec) running on my Z and Id be driving along, sometimes full song, sometimes much less, and it would backfire and then die. Sometimes simply by turning the key to full off and then back on it would come back to life . . other times I would have to replace one of my ignition modules, and other times all the settings we had put in the computer would be gone!

 

I went thru 7 ignition modules, replaced my alternator (looking for spikes) checked all my earths, sent my computer away to have it upgraded (wasted money) and eventually trashed the computer and put in a Motec computer.

Not only did the problem go away but I picked up 70Kw (93hp) at the rear wheels!

 

Unfortunately I never did find out if the problem was "just" the computer or something else as well, but I have always thought it was just the computer.

 

I think the old Injec computer used to loose top dead centre and this is why Id get the backfire and also why sometimes when I turned it off and back on it would pick up and go like nothing had happened. . . . how do you pick up top dead centre? thru the distributor or have you got sensors and a chopper wheel on your harmonic balancer? If the wiring in this area is a bid dodgy you computer might be losing top dead?

just a thought.

 

Cheers - Zbuild

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Antman . . .

 

The motor is bored 80 over . . . so 88mm pistons (forged), 240 Z rods, but no diesel crank. So its just bored but not stroked.

 

So i'm in Nashville and headed to Atlanta tomorrow. The Z is getting pretty decent gas mileage . . . 24mpg.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fine . . . . Fine!!!

 

I had the crank pulley off multiple times this winter trying to get the sds magnets straightened out. Well . . . I guess the last time it went on I forgot the washer!!! So it was wiggling and the sds didnt like that and started the misfire issue. At least it was a quick fix, but i feel like an idiot.

 

Oh well, Car runs good now!

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Hey Garrett' date=' I could top that with [i']several[/i] dumber things I've done, but I won't.:) .

 

Glad you got it figured out.

 

Give us Florida types a call when you get down here.

All right, spill it!!

 

j/k :D

 

Garrett, that's not bad. I forgot to tighten my turbo outlet charge pipe, and wondered why my vacuum was so low, and why the car hissed like crazy on boost. Oops...

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sure thing! Car goes on the dyno again on Wednesday in Orlando. Zgad and I are gonna get some tuning done and what not.

Where you getting the engine dyno'd? You gonna stick around that evening and run it? I am trying to get some miles on the engine and work out some bugs so I can make some low-boost passes myself.

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