the turbo is not what it seems. I used 2-1/2" exhaust pipe to start the inlet ducting (not finished). Its supposed to be TO4E 60 trim

 

Ah, ok. With it being such thick wall, looks huge haha. I have been using 14ga for turbo headers and haven't had any problems yet.

 

The #1 connecting rod journal was machined too small which probably caused the bearing to wear and spin right away. We swapped out that rod through the bottom end and put the motor back in the car today. Still a lot of work left before it can be started. Its too cold outside.

lesson learned: don't get lazy, check ALL clearances no matter how much you trust your machine shop.

 

I feel bad for ya. That happens so often it's not even funny - even seen it happen to $5000+ short blocks and they guys had to actually fight for some restitution from the vendors

No matter what, even if it's plastiguage, it takes a lot less time to double check during the process rather then have to pull everything apart.

Glad you found the issue, too bad you weren't here in FL we have had record highs this month...

 

The engine started up today and we ran it for a half hour. I still need to figure out how to get the timing advanced in the ecm. it was way too retarded (probably the 60* as expected) so I had to run it with the connector unplugged and it searched between 7* and 9* the whole time.

edit: and the tach doesn't work.

 

It starts up first shot after messing with the crank fueling (I forgot I had messed with it before and just put it back to stock V8 calibration). Everything was very lean (18:1 AFR on the WBO2) as far as idle and revving it up. So I decreased the injector constant a little. Idle was still too lean (BLM=168) so I played with the first MAF table and it seems to be ok now. next step is to bleed the brakes so we can take it off the jackstands for some test driving.

 

Got the timing settled? Glad to see another running.

 

yes, the spark plugs are firing at the .bin specified angle, but the chip still needs work. I increased the entire 'spark adder vs coolant vs lv8' table by 60*. Changing the offset value for that table (from 20 to 80) actually negated all the changes to the coolant table as measured with the timing light.

Max spark angle is now 90*, which is 30* advance. That should be enough? I could make it 38* since the actual base timing is 8*BTDC by "cheating" the initial spark advance angle to zero and decreasing the main spark table.

 

30*'s probably isn't enough. Some of the stock 3x00 tables can get into the 40's at cruise, although I doubt you'll need that much. Why not take 8* out of the coolant table? That would make tuning the main table a little more straight foreward.

 

video:


http://www.youtube.com/watch?v=tmw3-yL5cmA

 

Sounds pretty good

 

thx

 

Sweet. Can't wait for some 1/4 times.

 

You and me both

I have 3400/3500 FWD times and am wrapping up a 3.4/3500 high CR-N/A app now - ttype should be low 13's at the least.

 

Maybe mid 14's with the open rear. Can't seem to get rid of the code 33 (MAF volts High). It occurs about 5 seconds after startup. I found that I made a wiring error with the power to the burnoff relay and MAF sensor. I corrected the wiring to the relays and the sensor, but maybe the sensor was already bad or I fried it. How do you test the MAF sensor? I can't seem to find a way other than datalogging and looking for correct gms/sec. I see about 150gms/sec at idle untill it throws the code and goes into alpha-N mode.

 

Ya it's trashed. Don't need to test it to see that.

 

Is the v8 tpi MAF sensor used on any other cars?

I tested the MAF sensor plug, key on engine not running (ref=engine block):
terminal A = .01V
terminal B = .01V
terminal C = 5.02V
terminal D = open circuit
terminal E = 12.4V

Key off all pins are open circuits.

 

replaced MAF sensor with remanufactured Bosch unit from Auto Zone. MAF sensor works and logs properly... sort of. The injectors are supposed to be 37pph, but I have the injector constant at 28.5 to get 128BLM/INT at idle and part throttle. plenty of tuning to go.

Loud pop from exhaust at 4000rpm, 4psi boost, 15.0AFR, 150gms/sec

 

I'm curious how long the maf will hold up under fi. Reman stuff isn't very accurate or reliable.

 

Reman is fine, have been putting reman parts in cars for ~15yrs.

Sounds like you may have a leak to me.


are you blowing or drawing through?

 

blow through MAF... it was like 10.5:1 under boost = inj const too low. A leak was my thought too, but I can't find one. Maybe all the accessories like HVAC, BOV, WG, power brakes, and PCV throw the idle reading off. I want to try putting the inj const back to 37 and boost the first MAF table (idle). I'm new to MAF tuning, but I think I understand the concepts. I recorded max 162gms/sec on the 160baud cable (converts to 21.4lb/min) at around 4000rpm 4psi. I need to get the 8192 baud working so I can log LV8 to work on timing easier.

 

Not for maf's. I've seen LTFT's change 10% between new & reman. Alternators, starters, ect. it's fine but not mafs.

Do you have a map tied into the datastream? LV8 isn't that great a load calculation. It's just an estimation.

 

no MAP, but I do have a vacuum gauge hooked up... better than nothing

 

Try the MAF in front of the turbo. Some older systems get fuzzy when the extra heat from the charge has been added. Actually the 3400/3500 turbo car, the MAF HATED being behind the turbo, but since it's was OBD2, it's a different story.

That's a crazy variance for a remaned unit. All they do is put in new components.

 

You'd think it would be closer, but (re)manufacturing tolerances aren't the same.

I've always wondered where to route the bov with the maf ahead the turbo. If it vents externally you go rich initially because that air isn't injested. With it routed after the maf the air's still injested, just later so maybe a leanout as the air mass slows down through the maf... but then there's some revision into the maf from the pressure differential so it may even out??? And if it's plumbed back ahead of the maf (remeasured) it should be pretty accurate because it's measuring what's actually moving to the motor, but probably goes rich because it's already calc'd for a larger mass of air that didn't enter the motor + what's remeasured. But it might as well be venting into the atmosphere if it's close enough to the air filter. My feeling is after the maf would be the best compromise... or maybe it's all a wash in the real world.

 

My Saturn Sky MAF is about a foot before the turbo. The BOV recirculates air directly into the inlet of the turbo, after the MAF. during blow off conditions, some air is still being consummed (say 15%) and the rest (remaining 85%) is put into a loop that flows through the turbo at (probably) a high speed and low pressure. The maf meters the air entering the intake that is replacing air consumed by the engine further down stream ( conservation of mass). To understand, it helps me to pretend for a moment that air is incompressible since the pressures are low... then the compressibility of air is your error in AFR vs time. Since air IS compressible, the MAF signal tends to lag actual air flow in transient conditions (most of the time).

Or just put the MAF near the throttle body and the BOV anywhere upstream of the MAF. very little delay. In this case you worry about the MAF sensor calibration/reliability. take your pick.

 

I'm battling a mysterious and scarey 4800rpm fuel cut. No matter the load or throttle position (or trans gear for that matter) the exhaust makes a loud bang and the car leans over hard at exactly 4800rpm. I was looking at the 8192baud data on my laptop screen and I was able to get the engine at 4750-4775rpm for a second or two then I nudged it to 4800 and it still did it. AFR in the 12's vacuum condition.

The chip was set to 6500rpm fuel cut rev limit (255mph cut). So I tried raising it to 8700 ...(6500*8cyl/6cyl=8666)... still cuts at 4800.

 

Is it a coincodence that 4800rpm=80rev/sec=>12.5msec/rev? I'm thinking about the asyncronous injector pulse having the same frequency... I also wonder if it has anything to do with most of the tables in the .bin ending at 4800rpm and interpolating from there?

 

subscribing... and that youtube video was awesome. If you kept the hood shut I would've definitely mistaken it for a cammed V8. Very cool and sounds the same.

 

Any updates? Guess I had better subscribe!

 

lower intake was leaking coolant two weeks ago... found a hairline crack (I used a torque wrentch at install, could have been pre-existing). pulled another intake at the junkyard the next day. Since then its been either raining, 18*F, or snowing outside for 9 of the last 10 days and expecting a couple more feet tomorrow into the weekend... so not much time to work on it.

 

I was playing around with the timing today and it cranks at 0*, I think because of the 50* I added to the coolant table, which would explain the crappy starting cold. I was under the impression that the icm handled cranking timing exclusively but this would indicate differently. Can someone explain the 60* retard in the ICM to me? Why the hell did gm do this in the first place?

 

It has to with the relation to the sensor and reluctor wheel, the stock 60* location is ~60* advance of the TDC of #1, unlike the reluctor in the dizzy.

 

That's what I thought too, but when you look at the crank reluctor in the block the trailing edge lines up with the sensor at #1 tdc. No offset. It shouldn't matter where the sensor/reluctor lines up compared to true tdc, just as long as they line up at tdc. Anyone know what's actually controlling spark during cranking?

 

Nothing for the early DIS years, the latter DIS cars had the 24x reluctor to speed up the cranking process.

 

Same as for our dizzy type systems, the ignition module. The ECM kicks in around 400 RPM.

BTW, I may have found a solution if you're looking at adapting the Buick DIS...

 

By the way, sorry for the hijack.

That means the icm removes the 60* offset while cranking and fires right at the #1 mark (or maybe the mark 10* after?), then adds it running. And I need to fix my sensor position, lol.

What were you thinking on the buick ign?

 

I've been digging around, let's just say that much, and I came up with some useful links I'll send you in a PM... Also have some pics and wiring diagrams. Anyways, hopefully not to hijack too much, but it looks as though it should work nicely with a 16196401 (94-95 3400 DOHC) ECM... Only thing with it is the cam trigger.

 

Finally got rid of the 4800 rpm mis-fire. I tried everything. Tons of tune changes. Tested coils, wires, connections, sensors, and all over again and again. I noticed some paint scrapped off the trigger wheel for about 2 inches then found slight damage to the tip of the magnetic sensor. I had the gap (engine off) set to about .050", but obviously they touched at some point in time. I took the wheel to work and had it "trued-up" on the lathe to reduce runout, which didn't solve anything. I repainted the wheel and put it back on a couple weeks ago. Test drove it and still mis-firing, but no paint was scraped off this time.

Today I reverted to the NTRPMX timing (400-6400RPM timing table resolution) which also didn't fix the problem. Then I unpluged the tach signal wire after reading a thread about a bad instrument panel causing mis-fire, which didn't fix it. I reinspected the trigger wheel and found some paint flaked off the edge again. This time I was frustrated and pulled the sensor back to make a gap of about 1/4"! to my supprise, the engine fired right up and I revved it to Who knows how high without a mis! I revved it again and once more in case it was just luck. Then the engine stalled when it came back down to idle. The chip still needs extensive tuning, which I was hesitating to do untill I got the mis-fire figured out. So the trigger wheel must be less than perfect even though the notches were CNC machine cut.

 

How deep are the spaces between the notches? Perhaps it's shallow enough that the sensor isn't able to fully break the magnetic field at times?

 

I forget 5/16" or 3/8"

 

Plenty deep enough then. Strange.

 

Car is running great on 4psi (supposed to be 8psi, must be the wrong spring in the wastegate) PE AFR is 11.8-12.2 right out of the box. Now, I need a datalogging cable. I was long-term borrowing an rs-232 cable from a friend who needed it back. I made a 2-transistor cable, but it's not great for fine tuning.

 

Nice!

Are you using the stock WG and actuator that came on the turbo? If so check to make sure you have a little tension on the WG spring when it's closed, other wise you may be hanging it open too much/long. I did just the opposite on the last turbo kit - made sure the gate was hung open a tad and will turn the boost up slowly. Each full turn on the gate actuator should be about .100" or so and all the turbo's I have pulled seem to have about one to 1.5 turns (in stock configs) before the actuator eye will slip over the WG tab. This is especially important when you used turbo off something else and clocked it.

 

Its an external wastegate from ebay. I'm thinking its the .25 BAR (3.63 psi) spring instead of the .5 BAR (7.35 psi) spring it was supposed to be.

 

fixed the tach today with the npn transistor inverting amplifier circuit.

 

spun another rod bearing with 300ish miles on the motor... I'm thinking bad block (oil passages)?

 

Have you considered that your turbo-manifold crossover pipe that is going right under the oil pan, without heat-shielding, is heating your oil up to the point that it doesn't lubricate the rod bearings, anymore?

 

Ceramic coating, heat-wrapping, or installing some kind of heat-shield between that pipe and the oil pan would probably help a lot in that regard.
Also, what weight oil are you using?

 

10w-30. Good point, you could be right about the heat, but I have a hard time convincing myself because:
-The pipe wall thickness is .110", and its 304 stainless steel (which has a thermal conductivity coefficient, k=16.3W/mC, roughly 1/3 of low carbon steel, k=54W/mC).
-It is the factory exhaust location with more clearance than stock.
-With only 4 psi of boost, a cool 12:1 AFR, plenty of spark advance, and a relatively unrestrictive .63A/R turbine housing its not storing much heat in the exhaust.
-This block spun cyl#1 rod bearing when it was bone stock at 50K miles.
-There has been a little bit of abnormal abuse due to the tuning process.
-Finally, it doesn't seem as hot under the hood as my camaro.
HOWEVER, now that you've mentioned this I will test it out. thanks.