flashburn

Hi all,

I've got a turbo II thats been modified quite a bit. It doesn't run after 25 minutes so I began taking it apart. Firstly, there are a million vacuum leaks so I am fixing those first, and it has four 550cc injectors all the way around. I wasn't sure how this would affect the performance of the car since usually the primaries are smaller than the secondaries.

Also, when I change the plugs, it will run for another 25 minutes. But I can't ever use the same old plugs twice. When I pull the plugs it doesn't look like they should be fouled there is no visible damage to them. But they just will not start the car after its run for 25 minutes.

Any ideas would be great.

classicauto

iTrader: (3)

First, 4 550's are what comes in the TII stock.

Second, whats been done to the car recently maintenance wise?

Spectator

iTrader: (1)

Hot start issue?

I bet you have low compression. I suggest you test it.
If you're TII is quite modified, meaning, it has a freeflow exhaust, and you still have 4 x550cc injectors and no 720cc secondaries, you run lean when you floor it, because your Stock 6psi becomes 10 to 11, meaning to much air for the amount of gas at high rpms... And running lean kills an engine.

Test your compression. And make sure you have 3 consecitive pulses for each rotor. (3 corners per rotor )

105PSI and up is good
90psi to 104psi is OK
90psi and lower, almost dead.

RETed

No.


-Ted

gear_grinder

iTrader: (4)

what year is it? if it has a sucurity system i might have somthing triped so it thinks its been stolen. but idk cuz i have a old *** 87 TII so no security, lol. i would still try reseting the computor though.

flashburn

Ok, I failed to mention its a new atkins rotary and holset GM turbo. I thought hot start as well BTW. BUT, even if the car sits overnight it still won't start. Also it has been hotwired to bypass the hot start issues.

So I haven't done a compression test, but thank you for the PSI numbers I will do that to be sure. I'd like to think a new atkins motor should be ok in terms of compression.

It also has no exhaust. Just straight pipes. I'd assume that it has a high powered pump because it doesn't show symptoms of running lean. It runs great at 15 PSI before the 25 minute mark.

Basically I think were looking for something that kills plugs? And it happens in 25 minute intervals like clock work.

flashburn

Is there a way to officially reset the computer other than jumping the wires on the battery?

flashburn

Sorry for the multiple posts but I wanted to be sure to get it all out there:

Maintenance wise, I haven't got a clue. I bought it with nice clean oil in it, so I know its not a total loss on maintenance.

classicauto

iTrader: (3)

I'd check to make sure that you're not running stupidly rich. Might even have a stuck injector or somethign that's fouling plugs like nobody's business.

Get a wideband put on it and go for a drive...

Wouldn't hurt to pul the fuel pump (pretty quick and easy) and verify what's in the tank. Might be a walbro or something which would raise the likelyhood of an over fueling problem.

What do the plugs look like after 25 minutes of run time?

J-Rat

iTrader: (2)

I suppose the question I have is, with that Holset, how much boost have you actually ran?

flashburn

15 lbs but is is much higher cubic flow rate.

the plugs look new still. Its not like when a car runs rich and blackens up the plugs.

I like the idea of running around with a wideband, but how would that address it running great for 25 minutes then just dying?

classicauto

iTrader: (3)

Because you said it cooks plugs in 25 minutes.

Might be lean, your plugs *should* look a little blackened...perhaps not after 25 minutes, but they shouldn't look like plugs ran in an N/A car.

dean23

will it just not start? or will it not turn over at all.

RETed

Uh, you're running 15psi on a brand new engine???


-Ted

Smoken'

iTrader: (1)

And on stock injectors? Your just asking for problems buddy. Are you running any kind of fuel management?

J-Rat

iTrader: (2)

He already HAS problems...

15 PSI on a holset with just 550s?

flashburn

ok, so i should start with a wide band O2 sensor to make sure fuel levels are good.

Is 15 PSI really alot on these cars? I come from the DSM world where I was running 14 PSI stock so 15 didn't really jump out at me.

oh, any special A/F ratio for these 7s?

J-Rat

iTrader: (2)

15 PSI on a stock fueling system is outrageous. AFRs are some source of speculation. I personally like low 11s. (11.3 ish), with a leaner spool area of about 12.5.

MidnightOwl

Hahahahahahah stock boost is 6 lbs or 8 lbs on a rotary. Crazy race cars run 15.

REHarrison

If tuned correctly, the stock FC turbo should be able to handle up to 14 pounds. Now with stock injectors, im not too sure.

flashburn

Ok, I've been reading up on injectors now, along with FPRs. The whole impedance thing is confusing? If someone could link me to an explanation of what impedance injectors I should be using with my stock 88 TII thats would be great.

I think I understand the amperage concerns with low and high impedance injectors, but I've got no idea what injectors my computer is looking for?

Also, how large of injectors can I run in my TII without additional tuning or a FPR?