ian kam

well got my car back today i now have guru stage one map kit..3" exhaust...dual lindsey wastegate. now full open throttle i'm 16psi of boost this still does not even come close to holding till red line. Shows i'm not running lean and while the rpms come down of throttle under load alot of backfires popping. I know tunning on a dyno has alot to do with this all because right now i'm not sure if a notice alot of difference. 87 944 turbo....any ideas?

adrial

It's a stock k26/6, some people say they hold to redline, others say no.

Even if you get it to hold to redline, there's not too much to be gained above 15psi.

You definetely need to get some tuning done on the dyno, see how your a/f curve looks.

Danno

How much does the boost drop in the upper-RPMs? Did you get the stiffer spring for the wastegate? You can acutally shim the Lindsey wastegate and reduce the drop to only 1-2 psi. I've got the chips mapped for a flat boost-curve, so your AF-ratio curve will most likely be around 12.0:1 in the mid-range and get richer and richer as you approach redline with a dropping boost-curve.

ian kam

danno i will let you know about when it drops and how much...is all this popping (exhaust) normal? Midrange deceleration under load. Never did it with just the chips but showed up after map kit put on

Madant26x

I think the popping has something to do with that new 3" exhaust you just put in that removed the cat. My car does the same thing when flooring it and then getting off the throttle. I believe it's because at the instant you take your foot off the throttle the car is running rich (still burning off the fuel even though air supply has been cut??? correct me if I'm wrong). But you would have never experienced this sounds before because of the cat.

mark944turbo

Yep, I have the same mods as you do minus the wastegate and mine pops as i descelerate as well. It also backfires when I am coasting in gear and then I give it just a tiny bit of gas. I guess this is normal. What worries me is some cop is going to think its suspicious and then find out that I have no cat.... Im thinking of putting in a high flow one just to be safe.

Madant26x

Man, I actually really love when the exhaust pops and backfires. I think it sounds mean, kinda like a track car, and it almost always has people's heads turnin.

Anyway, last time I was at the track, which was the first time since putting on my full exhaust, at the end of the front and back straights I was at about 6,900 rpm and when I lifted to brake people said flames were shooting out my exhaust !!! I was putting on the afterburners .

ian kam

well my cat was off prior to this but i think im going to go with a high flow cat. I do nitice if i keep my foot completly off the gas pedal i get no popping...so i think my cable is to tight needs more free play. more than likley keeping throttle open a little causing it to run way to rich ....causing the backfireing. Just a idea... will this high flow cat make the car not so loud?

Jeremy Himsel

Does anyone know what the rev limiter is set at with the guru chips??? I noticed as post of 6900 RPM's but it seems that I hit the limiter much earlier than that with my guru chips.

Madant26x

I don't really know what the rev limiter is set to, but I think I saw it hit 7000 before the fuel cut-off kicked in, but maybe that was just a slight inaccuarcy of the tach. I think I heard the Guru chips have a 6,800 rpm limit, I was just going off of what I saw on my tach.

Danno

I actually use the stock 6480rpm redline. Typically momentum can carry you over that. But if you keep it floored at redline, it eventually stabilizes and stays at 6500rpm or so.