Tuning cousins T-Type for him currently, some issues I can not get to go away currently.. Like a phantom dead spot at around 5200, once past it pulls hard, also a dead spot when leaving under boost just after throttle transition.. The phantom, the car came with a turbo tweac chip or something and ran like poop, I have the driveability much better after playing today, but this hard acceleration, maybe tip in is driving me nuts and the phantom dead spot.. It has done the same thing with the Turbo tweak, what I think is a vergin T-Type bin and the Turbo ta bin.. I can move it it seems but will not go away..

Anyone have a vergin T-Type bin? What timing should I look for with 15 psi and stock intercooler? It seems the Dead spot may be happening just as the maf hits 255 if that helps?

 

Really no turbo buick guys here? there used
to be a few.

 

Sorry, I got so frustrated with trying to tune the '7148, that I am swapping my friends TR to a '7749 and will be running $59 on it.

 

Thanks, its very frustrating, it sooo slow and reacts weird.. Had been tuning idle for a while scaling the MAF tables, had it right at 128.. A few burns later while getting part throttle dialed in it begins pegging 150 at idle again! However I think we just found yesterday the 02 went out of the car.

Any idea what the dead spot is, it actaully sounds like hitting the l8imiter but its not, but just found also when running alcohol inj it does not do it.. So I am guessing a lean spot?
One quick question, the Fuel trim table, posative # means adding fuel right? The word trim is baffeling me, I keep thinking trim as in remove.

 

Sounds like the MAF is bad and/or on the way out. Aftermarket replacement MAFs are no better then a bad GM MAF. This is one reason that the translator boxes and LT1/LS1 MAF combo's are so popular on these cars.

Note that at idle and low speeds, any vacuum leak will cause high fuel trims (BLM values). Above 128 is adding fuel. The vacuum block on top of the plenum is a common leak point. Same with the PCV. Check all vacuum lines.

If using the waste gate solenoid, as in the stock set up, double check that it is plumbed correctly. The 'Y' fitting has a restriction in it that must be plumbed correctly. Otherwise the boost control is wrong.

gnttype.org has the proper plumbing layout for the waste gate set up.

RBob.

 

I,ll check the block and other vacuum sources, he has an aftermarket boost controller currently, but I can't help but think its something to do with when it activates though, being it happens so abruptly. but then once you pull past it pulls strong again.. hmm.

Also can you scale the MAF tables above 255 to add fueling to areas?

Rob, I see in the fuel trim there is a large shot of fuel added at 2400, I am wondering he has a 3200 stall in the car now, should I move that shot upward to where the new converter is stalling?

I am still thinking the idle issue was the o2 being he was running about 50/50 race gas at the time. As I got the fuel right it idled much better telling so it needed it, but there could be an intermittent leak as the engine moves I suppose maybe. It was just strange it had been rock stady for several burns,then out of nowhere max lean.

Last question, that thing has a map sensor on the fenderwell not in use, what is it for?

Thanks for any assistance..

 

Can't easily scale the MAF tables above 255 gms/sec.

> I see in the fuel trim there is a large shot of fuel added at 2400

This is the INT & BLM suddenly increasing? I'd say the MAF either isn't reporting correctly, or the MAF table needs to be increased at that air flow.

If the race fuel had lead in it, then the O2 sensor will be affected. Takes some time but eventually will die.

One thing about tuning these cars is that monitoring the fuel pressure and the boost is mandatory. There is a lot of the Walbro '0169 pumps that are bad. They get flakey before finally dying.

So keeping an eye on fuel pressure is important. It must also rise 1-for-1 as boost builds.

Of course monitoring boost is required to know what is going on.

> Last question, that thing has a map sensor on the fenderwell not in use, what is it for?

Boost gauge. The LED thing in the lower right in the cluster. By now probably doesn't work correctly. It also has a RPM LED bar gauge.

RBob.

 

Thanks, good info - I did not realize the regulators were boost referenced in these cars, that helps.

Sorry I did not explain well, I meant the fuel trim Table, Fuel trim vs rpm in PE. The table adds like 18% fuel at 2400 than pretty much 0 after that. This car also has a dead spot just after wot like 3200-3400ish, I am assuming that large increase probably needs shifted up to where is converter is stalling.. My WB is broken or this would be much easier right now.

Thanks again for the help.

 

Those trim values don't appear to be correct. Looking at a '89 TTA BIN it is richer at 3200 and 4000 RPM. At 3200 the BIN value is 141, and 4000 the BIN value is 134. Ah, but a t-type BIN has 128 at 4000 RPM. Which is what you are seeing, no change. Bump it up.

Looking at another calibration, not sure what one it is, the values in that table are:

128 ; 800 rpm
130 ; 1600
132 ; 2400
134 ; 3200
135 ; 4000
137 ; 4800
137 ; 5600
137 ; 6400

The left hand column are the BIN values in decimal. Over 128 is adding fuel.

RBob.

 

Here is the screen shot from the Bin I have using T/C, The calibration you showed makes sense being it steadily increases.. I like to format your is in, makes more sense.

Little hard to read, sorry. But those are 0's at 4k and greater, Kinda looks like 8s in the pic.

Would you happen to have a vergin T-TYpe bin? I am concerned mine is not that I got from Moates site. Can not find any anywhere..

Thanks again Rob,

 

% change reminds me of PE enrichment in 6E MAF setups. Try giving it more fuel at the converter stall point. Load rapidly increases at that point as converter tightens up, so it would want to go lean. Try a bit of enrichment there and see what happens.

 

Yeah, thats how I was leaning, assuming thats where the stock converter was stalling near, now with new converter I will shift it up. Still an issue at 5200ish, just need time to play with that now.

 

Whens boost coming on strong on this setup? Anywhere near the 5200 rpm range?

 

Start pulling strong well before that it seems, I would say it may be opening wastegate near there.. I did notice it right as the maf hits max 255gms.

 

With the MAF pegging, no more fuel is added from the MAF. The extra fuel has to come in from somewhere. Sounds like not enough PE mode enrichment? I'd hit it with some more fuel in that 4800-5200 rpm spots with PE and let it eat. That makes sense to me but I'm not familar with these turbo buick motors.

 

Now, that makes a lot of sense to me actually.. Thanks Justin..

 

Sorry to bring back old thread, figured I would post the cure for the issues.. Happened to be valve springs, lightest had only 40 lbs on seat.. After some more searching on turbo forums found that to be issue.. Thanks for any help, it was strange it happened right at 5k and would pull after, I guess due to the max hp/cylinder pressure time...