Rich boost issue

[Cidacious]

While working on the car I observed that there are coolant lines running to the turbo via tri taps on the coolant lines running to the radiator at the front of the car. Is this some kind of poor man's intercooler?? Over the weekend I also replaced the plugs (NGK iridium IX), wires (accel 8mm) and coil (msd blaster). The distributor/rotor is on order. I also purchased an MSD ignition 6al box to better burn fuel under high rpm (not installed waiting on harness to be delivered). While I was there I told the advance auto parts guy about my AFR 10.0 under boost. He suggested to turn up the boost to burn the extra fuel. That got me thinking the previous owner had told me that when he bought the car the previous owner/builder turned down the boost for him to 8PSI. That got me thinking if he mechanically turned the boost down, but did not update the prom with the new parameters the car would be very rich under WOT, right? The advance auto parts guy said to turn the boost up to 10psi and see if that burns the extra fuel. I have also read that going above 6-8psi is not a good idea if you are not intercooled. Since there are coolant lines being sent to the turbo, then is it not intercooled? I know as a rule one should ignore the advice of auto parts stores, but this seemed to have a grain of logic. What are your thoughts?

[Cidacious]

Oh, even though the car runs smoother and idles at about 900 now when hot, it is still a solid 10.0 under WOT boost. (I think that is as low as the guage goes...)

[ghrarhg]

The coolant lines running to the turbo are stictly for that purpose, cooling the turbo. Nothing to do with the charged air. Not all turbos are water cooled, some are just oil cooled, sounds like you have one that is water cooled if the lines to rad are tapped into. Depending on your tune, cranking up the boost will not likely affect the rich condition. The ECM will add more fuel for more boost.

How is fueling being handled. Stock FPR?

What code mask are you running your engine with?

[Cidacious]

stock fpr, I think it is the 8$ thing, but I don't know, there is a custom chip and stock ECM

[ghrarhg]

Well, for what it's worth, $8F was pretty damn rich from the factory. To me, it sounds like it's all in the tune. Nothing to do with level of boost.

Also, the lack of intercooling may have been what drove the previous owner to run it super rich. Better to run rich and foul some plugs than run lean and blow shit apart.

[robertisaar]

"He suggested to turn up the boost to burn the extra fuel"

i wouldn't be listening to any more tuning advice from this person....

and this is the stock ECM to a fiero? those were 1-BAR MAP masks... on an old C3 ECM...

[Cidacious]

In messing with tunerpro rt, I saw a switcher for 2-bar map, and I have purchased a 2-bar map and connector as I cannot prove that the map on the car right now is a one or two... With this switched, can the stock ecm run a 2-bar program?

[robertisaar]

a fiero ECM would be running on a 24 or 24A mask(depending on year, the A is 85 only)

whoa, WTF? i see the flag, but does it actually work? i need to see if i can find a hack...

[robertisaar]

well.... i took a look at the XDF, and the flag is indeed there, but the problem lies here: there are exactly 0 constants and tabkes for dealing with either spark or fuel above atmospheric pressure... and the VE table is tiny at that. i don't see any way of accurately controlling fuel when it gets above 100kPa other than expecting the boost to remain VERY constant based on RPM and adding fuel through the base VE table.

long story short: i don't know WHY GM put a 2BAR switch in the code, but it seems that's the only thing they did to make it capable of reading boost(if it even works)... no way would i even suggest trying to run boost on something made specifically for 1BAR.

[Joseph Upson]

24A available for the 85 ECM only is the appropriate bin for boost as well as the addition of a Knock sensor with the use of the appropriate external ESC module. There is a 2bar select option in the constant for year 86 up but it lacks the code accomodations found in 85. You can't just select 2 bar in the 85 bin and add a 2 bar Map sensor, the spark table will have to be rescaled and likely the fuel table as well. I never succeeded at getting the 2 bar version 24A code to work because I was unaware at the time that my hardly used 2 bar MAP sensor was bad.

On some MAP sensors you can tell if it's a 1 or 2 bar by looking closely at the top of the sensor in the small web area to the left of the plug. There maybe a small number there. I don't have my 2 bar handy but recall seeing a number around 2 to maybe 2.1 for the 2 bar and 1 or slightly more for the 1 bar. You should also be able to run the part number on one of the part store websites.

[Joseph Upson]

no way would i even suggest trying to run boost on something made specifically for 1BAR.

That's very wise, but in the early days of boosting computer controlled cars it was done effectively even by big names such as Paxston. I did it for years until more information and access to engine management controls came available. If you understand how the ECM functions along with the fundamentals of engine operation it's quite easy, however, you will be limited in how much boost you can run before richening fuel and reducing timing in the chip at 100 kpa just isn't enough. For me that was 7 psi, but it could have been the result of overwhelming the injectors or fuel pump that put up a wall when I tried to achieve 10 psi.

[robertisaar]

true, but these days, those comprimises don't have to be made... and for the price it runs to do it right, i can't see someone justifying using stuff like RRFPRs anymore(unless you REALLY need the extra pressure along with proper tuning).

[Cidacious]

I installed the MSD 6AL ignition box and now at first at WOT/boost it is a 10.0 and then as the RPM's increase to red-line the AFR goes up slowly to 12.6 just before I lift. Is this, in your opinion not too lean? what range is goal boost afr?

[robertisaar]

depends on the motor... someone on w-body just had their 5 speed TGP dyno'd and after looking at all of the fuel spikes/dips, it seemed to make the most/smoothest HP/TQ at 11.6:1 according to a WB(not sure if it was a tailpipe version on the dyno or what).

[Cidacious]

hmm, okay how would I know if I am too lean then?