SERIOUS problem: tuning gurus needed.

[disco stu]

Okay. I have a problem with an engine that I thought I had licked. It had melted a plug off in the engine, taking out a piston and a head. I ended up suspecting the injectors and had them flowed. That injector flowed almost 20% lower. So I thought I had found my problem. So we replaced the 75s with 85s. So I repair the damage and get the car going again. Short 3-5 second blast on the street, everything looked good. I started at 19 degrees spark, 18 psi, and 10.6 AFR. I crept up to 21 psi, 21 degrees, and 11.0 AFR (ALKY). EGT's were on the cold side, and no knock. Seemed safe enough to start tuning at the track.
So, first pass I blew an intercooler hose off about the 1000' mark and coast a 10.2 @ 121. I was quite optimistic. Unfortunately I forgot to arm the datalogger. But I knew the tune was on the conservative side and o2 corrections were less than 1% previously.

So, I go to run it again after checking some stuff over. Then the same problem rears it's ugly head. EGT's were high 1300-low 1400's. Til about the middle of 3rd. Then #1 EGT skyrocketed. Did not percieve anything wrong during the run, but slowed to a 10.3x at 129. Checked the log, and knew something was wrong. It was adding fuel and the EGT rise made my stomach sink. Pulled the plug, and it was done. Dropped 50 psi compression on that hole.

It has a homemade double pumper with 2 -6 lines off each pump, Y'd to a -10, -6 return. Saginaw fittings cut off and AN fitting welded to the rail. Both pumps were flowed and were deemed good. FP is verified 1:1 rise, with 45 PSI static. It fueled my car to 141 MPH without alky and showed no signs of dropping off.

I am going crazy. Injector driver? Wiring? Injector harness ohms good, and pins look new. Have not checked the rest of the harness yet.

Anyways, look at the log and let me know what you think. I took up alot of slots with EGT on the dash. I wish I had some other things logged, but take a look and see if you can see anything wrong.

Combo:
109 stroker, 8.5:1
XFI
70 GTQ turbo
224/224 hydraulic roller
Race ported GN1's

 

[disco stu]

Oh yeah, alky pump is good I believe. Also, if it were a alky or fuel issue up to the injectors the rest of the cylinders would have indicated such instead of being isolated on #1

 

[disco stu]

Also, note the #1 egt tracer while on the 2 step. It's not consistent with the others. But does not show much deviation up until the problem.

 

[Scott Atk]

Sorry, I can't read the logs my network has it blocked, were both instances were #1 hole??

If so, does the car still have the stock fuel rail?

 

[norbs]

1st thing you need to make sure your fuel pumps are flowing 1.5 gal /per minute @75 psi, not 45 psi. If not go to a big external or put a kenne bell boost a pump on it and reflow.

Can you email me your compete datalog I'll look at it some more. Even though your injectors flow the same, sometimes the intake flows uneven. On my car i am adding 20% more fuel to Cyl #1 to keep the egt's within 50 degrees of each other, and all my injectors were flow matched. Have you verified the timing matches the xfi timing on your maps?

 

[whiplash306]

Subscribing as the owner of this unfortunate mess....:frown:

 

[Jerryl]

That sucks! Stock rail?
I read a thread somewhere where #1 runs lean on faster cars. (I never had to worry about it )
Not sure if I can find it and don't remember the fix.
(Maybe the fix was the installation of Champion fuel rails ....... I think )

Edit.
Here is the thread.
http://www.turbobuick.com/forums/pe...mps-injector-drivers-go-bad-bad-injector.html
Sounds real similar.

For the record:
I am no guru, but I DID stay at a Holiday Inn Express last week.

 

[MSDGN]

You should log your Actual A/F also...10.9% O2 correction at frame 140...what was it the rest of the run...that tells me it's trying to add a lot of fuel

 

[disco stu]

Yes, this happened on the same hole twice. Yes it is the stock fuel rail, and this has had me wondering too. I had not thought about that before, but when the possibility was explained to me it made sense. The I.D. of the rail is pretty large, but since pressure is relieved closest to #1 it is a possibility.

Timing is accurate.

I think that pump volume is adequate as pressure is steady, and injector DC is not a problem (though it was not logged on this run).

 

[disco stu]

You should log your Actual A/F also...10.9% O2 correction at frame 140...what was it the rest of the run...that tells me it's trying to add a lot of fuel

I'm thinking that it was because the average was down that much because of a lack of fuel on #1. Since it had not met the correction limit, it was correcting that much to maintain the 11.0 AFR.

This is a bummer, I know that the car has potential to make good power without leaning on it too hard. Just got to quit melting motors. :frown:

 

[V6RACER]

Definately a fuel delivery problem.. What times are you trying to run with this car?

 

[disco stu]

Goal was easy high nines. Looks like it will do that on a street tune since it coasted a 10.2 on an easy launch.

Fuel problem was my first thought. But seems that it's only on a certain cylinder. And it's all of the sudden. Like I said, 3-5 second blasts, everything looks normal.

 

[norbs]

We don;t know the a/r ratio, but it looks like at the maximum correction point you can see #1 cyl getting hotter right there. 1650 max looks like, but that doesn;t seem to hot to start melting pistons, I could see maybe 1900, but this doesn seem very strange so far.

Your guessing your fuel system flows enough without flowing it at 75 psi? I was shocked when i flowed mine. I think you should check it. can we get a pic of the spark plug?

 

[Scott Atk]

I melted #1 at 11.4 a/f ratio.(Norbs may remember this and our private discussion) Now I don't go over 10.8 when spraying ALKY. Still using the stock rail without further problems.

 

[Otto J]

Are you damn positive that second pump is coming on?

 

[disco stu]

They both run full time, and I am positive that they both come on and that the FP is good.

This is most definitely an area that would be the first concern. But I would think that it has to be something else since it seems to be something that is not happening across the board.

 

[bison]

Id re-flow the pumps as norbs suggested and run a dual fed set of aftermarket rails like the ones champion sells. Just Y it under hood and run a pair of -6 to the rails. Running retarded timing will raise EGT's. I would creep up on it a lot slower next time. Like let off after 7 sec and review. Then 8 sec and review. Then 9 and then full pass. This way if it goes lean it wont have enough time to melt any thing and you can look further.

 

[gnxtc2]

Are you damn positive that second pump is coming on?

+1

How is the 2nd pump activating?

I would junk the double pumer set up and install a big single. Add a set of Champion rails. You have the -10 already ran. In the engine compartment, "Y" the -10 and feed each rail with -8.

Billy T.
gnxtc2@aol.com

 

[disco stu]

I melted #1 at 11.4 a/f ratio.(Norbs may remember this and our private discussion) Now I don't go over 10.8 when spraying ALKY. Still using the stock rail without further problems.

At what boost level? That is quite lean for pump alky. Hell, maybe 11.0 is a bit lean for alky, but I did not think so for 21 psi and 13XX* egts. It will be richer beyond that, but the bubble was not there yet. I started at 10.6 with the tune at that boost level, and had some knock, it stopped when I went back up toward 11.0. it does get richer in the cells above that, but I have not gotten there yet, and was not planning to by much.

 

[disco stu]

Id re-flow the pumps as norbs suggested and run a dual fed set of aftermarket rails like the ones champion sells. Just Y it under hood and run a pair of -6 to the rails. Running retarded timing will raise EGT's. I would creep up on it a lot slower next time. Like let off after 7 sec and review. Then 8 sec and review. Then 9 and then full pass. This way if it goes lean it wont have enough time to melt any thing and you can look further.

I agree, I'm kicking myself for not doing so. I thought it looked good enough on the street and went for a full pass. I was wrong.

Running retarded timing will raise EGT's but lower cylinder temps and pressures since more of the heat is getting let into the exhaust.