Intercooled 2.5...
Anybody have any guidelines on how much timing I should have out at 10 psi? 20 psi? It's running pig rich at the moment but lighting the cel @ 10 psi by around 4000. Is there any kind of general rule like pull x degrees of timing per every y psi increase in boost? I'm trying to get the timing sorted before I start working on getting the fueling straightened out.
Thanks,
Tony
I would look at the timing in the stock "high torque" cal (although I think only the boost is different between the two from what I have read) and start there.
I would get the AFR sorted out next, and then work my way up toward the MP timing very slowly testing it every 500RPM while dragging the brakes. (Can anyone tell that this was my favorite tip from the SDAC tech session this year?) Watch your EGTs, AFR and CEL while you do this and all should be well.
The thing is it's lighting the cel at 10 psi with the original timing in the base cal unchanged and the distributer set at 12*. I even pulled a couple degrees at 10 psi in the full throttle and part throttle tables and it had no effect.
I can't help but wonder if it isn't mechanical noise causing a false trigger. The engine is a bit noisy even though it has fresh bearings and carries good oil pressure.
If you have access to a scanner, I think you can see the "noise" from the knock sensor. go through the RPMs while someone documents the volts every 500RPM and use that to adjust your knock table if need be.Originally Posted by Tony Hanna
Any particular scanner to look for? Hopefully something inexpensive I can pick up used from someone here or ebay...
Thanks,
Tony
You will want to ask someone like Bucar, but I believe the OTC 4000 does this. I have been passively looking for one since SDAC. There were enough guys running around with them that I got to see a little of what it does, and they are well worth the $100 or so that some of the guys were saying they paid for them.
Yeah, for $100 that wouldn't be a bad deal. I'll have to do some searching on ebay and see if I can track one down.
Hi, I have discovered a completely new aspect to the CEL coming on in boost. I did have the same issue with various cals and went mad changing timing etc. with no result. Eventually I figured that the CEL would come on less once the engine is warm.
But eventually I figured another problem. Between the Baro Solenoid and the MAP Sensor goes this small vacuum line. Now, checking on the solenoid side I figured that it was quite lose (you'll notice that the MAP port is much thicker then the Solenoid port. And bingo, in my case at around 10 PSI it bled pressure into the air thus the Map reading did not change for a while thus it switched the Check Engine Light for this moment. Letting of the throttle, the map starts reading again, check engine goes off. so, swapped that with a silicone line an tied it to the ports. Never had check engine again.
Now, this is one possibility, but it usually would leave code 13 stored in memory. Other one is, that it bleeds pressure and the map does not read all there is, thus the ECU assumes less boost then there actually is.
Anyway, beleive it or not, I now run the timing as set in the popular cals and don't have the check engine at all or if so really rarely close to redline.
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tony, though they are for LM cars, take a look at my base cals that i have for the 2.5L in regards to timing. i took a deg of timing out of the govner from 2800-4000 and that seemed to help. i also ramped down the timing from 14-15psi to 29.4. it only ever seems to pull out 1 deg at 18psi sometimes, usually on a higher gear roll on. i also had to add a little fuel right around 3000 as seen in the pumping efficiency table as it was lean during roll ons.
otc scanner... i have one. it does display knock voltage. what you want to do is hook it up and go for a drive. back the timing off with the dist a little or with the govner table prolly 1 deg. put in some race gas. do some 4th gear roll ons and if the cel doesnt come on you should be fine. make sure you have stored vacuum in the brake booster (decel a bit in gear) and then hit the gas and the brakes to stay at a set rpm and wait till boost stabilizes and the knock voltage stabilizes and that should be the background noise that the knock sensor is seeing. write down the rpm that you held the engine at and the knock voltage. repeat. then go up 500rpms and do it again. keep doing this till you have a chart of rpm vs knock voltage. take a look at the points in the knock vs rpms table dltknk i think. they should be a little higher than the values that you datalogged. ~5-10% higher.
jeff chojnacki wrote a program, SMECLog that does the same thing as a scanner but you have to make a SCI connector to RS232 interface. http://www.schmartboard.com/index.as...opulated&id=84 here is the one i use. you connect it to a +5v source (TPS or something), ground (fuel rail bolt) and the TX and RX wires on the SCI connector or at the smec connector.
Brian
btw, do fuel first. its easier. if you do timing with regards to knock and then lean the car out, youll be doing timing again.
Thanks Brian! I'm going to work on the fuelling some more this weekend and hopefully get it sorted out finally, then I guess buy a scanner and work on the timing next weekend.
What's really bugging me is that the timing in the base cal I'm using when compared to a stock TI cal in D-Cal is exactly the same. I can't see why at 10 psi I should be getting any knock at all unless it's mechanical noise, a loose MAP vacuum line like MoparBCN mentioned, or maybe the pistons/chambers being carboned up really bad from where it's been running so rich. I was having no problem with timing before the head came off aside from having to pull a little at 18+ psi which solved the problem.
you might have been getting knock from being too rich. that sometimes happens.
Brian
Really? That would be great if it's something that simple!
I've always heard that a rich running engine was more prone to knock because of the carbon both increasing cr and staying hot enough from the previous cycle to light the charge on it's own. I just never thought it would have that noticeable of an effect.
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