high map on hwy

**PJG1173** · 03-10-2012

for the timing table I copied the table from a 98 s10 4.3 with an efilive eval. it took bumping up the timing considerable amount to get the motor to come alive and get to this point. I'm going through some of my old datalogs from before the CDI install to see if there is an hints of high MAP around that speed. I didn't really pay attention to it since I was more working on cruise in town. Yes the cam was degreed when it was installed. I had it in 4lo a couple nights ago doing some hole shots in the mud when I went to pull another truck out. all the guys out there could say was OMG thats a v6?, so yes it comes to life with more rpm.

**PJG1173** · 03-11-2012

ok so after a busy afternoon messing with the truck I am no futher than where I was before. I bypassed the crane CDI which didn't do anything for me. sprayed everything semi flamable and propane at the tb base and adapter no vac leaks. I played with the timing adding 3* in the high map around 1600 - 2000 and there was no change still 95 - 100 kpa at 60mph. I loaded a CPI timing table which was similar to my modified vortec table and still no change. I then copied the stock spark table and it struggled at 50. I put a 4 wire NB O2 in with the ground attached to the block. no change there either still reading the same as the old one. without knowing if the knock sensors are working I am a little reluctant to advance the timing any more than I have.

**RobertISaar** · 03-11-2012

you know... maybe you've just lost that much lower RPM torque?

**PJG1173** · 03-11-2012

thats what I'm starting to think. I'm sure if it was sitting at stock height with stock gears and tires this wouldn't be an issue.

**EagleMark** · 03-11-2012

5:13 gears?

**gregs78cam** · 03-11-2012

Ok, let me get this right.....95-100Kpa, 2000rpm, and 60mph. At that MAP, you are essentially WOT, just without TPS showing it. If you do go WOT does it accelerate through that spot with the addition of PE?

266HR should give you plenty of torque for that truck. 4.56s with 36s should not make a big difference in final drive ratio from stock.

**PJG1173** · 03-11-2012

yes if I go WOT it will accelerate to 80 - 85 no problem.

**EagleMark** · 03-11-2012

Originally Posted by gregs78cam

Ok, let me get this right.....95-100Kpa, 2000rpm, and 60mph. At that MAP, you are essentially WOT, just without TPS showing it. If you do go WOT does it accelerate through that spot with the addition of PE?

266HR should give you plenty of torque for that truck. 4.56s with 36s should not make a big difference in final drive ratio from stock.

That's what I thought too. When I searched real quick RPM was 1400 up but he said on a 4.3L it's 1800 up, he's right at 1800ish...

So if you got passed that point to 80 MPH does it have power and same vacuum?

You could always degree that cam... ahead right for lower RPM? I always get that mixed up...

Greg did you see his data log at that speed? His WBO2 was swinging about 1 AFR, shouldn't it be more steady? He was running open loop. Now that I think about it was 14 to 15ish, I wonder if he got it down a little would help?

**RobertISaar** · 03-11-2012

open loop and swinging are generally a bad combo.

and yes Mark, advance the cam to shift the powerband lower, or at least that's the way i remember it.

**EagleMark** · 03-11-2012

Originally Posted by RobertISaar

open loop and swinging are generally a bad combo.

Wouldn't that be a missfire? Or?

**gregs78cam** · 03-11-2012

Can you tell us your air intake setup? Just like stock? or modified? how so?

**RobertISaar** · 03-11-2012

hmm.. possibly. assuming the VE was done correctly and the VE swing wasn't caused by AE/DE, then yes, i would look for a soft misfire.

**EagleMark** · 03-11-2012

At steady TPS 1900ish RPM 90ish MAP 60 MPH no AE or PE and WB AFR swings about 13.9 to 14.9ish? Never steady?

**PJG1173** · 03-11-2012

Originally Posted by gregs78cam

Can you tell us your air intake setup? Just like stock? or modified? how so?

I have a edelbrock 2114 vortec intake. with a mr gasket squarebore to speadbore adapter and a transdapt tbi adapter. I have an airaid CAI from the tb to the front driver fender. filter is segregated from the engine compartment by a box.