Uncontrollable Boost - M20 w/ 6262

[varg]

Much better. Burn those tires up and replace them asap so you can start enjoying the acceleration.

[mikey.antonakakis]

Woohoo!!

[Evan_VRM]

Well we had another problem at the dyno today. This time it was that my 7 year old 205-width tires were slipping on the rollers. Despite that, the car made 347 whp at 16psi. I am finally comfortable driving it now and the difference is awesome!

[mikey.antonakakis]

Glad you got that sorted.
For the moment, I've only been able to street tune my VGT setup, but I built some electronic det cans that work pretty well. We only get 91 octane at the pump here, and I am almost certainly losing some power with my current timing (I tuned out all perceptible knock, and run pretty strong MAT retard).

My car isn't sluggish, but after a few pulls on a warm-ish day, I was seeing just 11-12deg advance at 180kPa MAP with the combo of my ignition map and MAT retard - from the maps I've seen, that's pretty conservative at that boost level. After those pulls, I drove for about 20 minutes at 60-80mph, which pulled the heat out of my water-air intercooler, and as I merged on the highway I spun the tires a bit in second gear (2.93 LSD with Direzza Star Specs), which it wasn't doing on the previous pulls. I didn't datalog that moment, but some moderately careful calculations of the earlier pulls showed about 280-300whp. Same calculations showed around 260-270whp at 155kPa, so not a ton of extra power for the extra boost, but I retard pretty strongly with boost at the moment.

Hopefully for both of our sakes, there is a good amount of power left in the ignition maps :) I'm going to try a tank of 100 octane soon to see how much I can bump up the advance and to see how the power responds. Interested to see where you end up.

[Evan_VRM]

Well as it turns out my M20 has the same crank wheel as all of your M20s. Timing was dead on at 0* fixed and the crank wheel settings at 84*. Tuner was embarrassed and is going to take another crack at it next Wednesday. He definitely pooched it "verifying" the timing. I didn't want to drive it too hard/far until I get the tune properly dialed in (and it was raining here last night when I test drove it) but you can definitely tell it is making more power.

[varg]

No. The timing table is inaccurate because the trigger settings are wrong.

From a tuner's perspective, the tuner is incompetent. OP said the tuner verified timing, it's obvious the tuner was not sure what he was looking at by the result. It's better to pull out your phone and search than to pretend you know it all and charge a client for substandard work because you didn't know what you were looking at due to lack of experience with their setup. Usually within minutes you can find the wealth of information available online from the many people successfully running Megasquirt on similar setups.

[LowR3V'in]

dang dude so u where running like 7* timing on boost?

[mikey.antonakakis]

I have a non-adjustable timing light, but was going to borrow a programmable one. This may be a stupid question, but will the car run with timing fixed at 0*?

It should idle, mine did with 60lb injectors, a little rough but it was good enough to set the timing. I probably had to bump up the throttle stop (or idle valve setting if you're using one).

[ForcedFirebird]

Dumb question: Would having the crank setting and timing completely off contribute to OP's boost control problem using the unmodified WG location?

Sure. If you are dumping expanding gasses in the manifold while the WG is trying to control said pressure. Now you are creating a situation where intake manifold pressure has less effect since the exhaust pressure is so high. OP should put a boost gauge on his exhaust manifold between the tubro/engine and see what kind of ratio exhaust:intake. Most decent systems will be around 1.5:1, but a poorly setup system will do 2:1 (or improper ignition timing - or ant-lag etc can also cause this), 1:1 is ideal but not easily reached.

You can use a fixed light. Just have to mark the crank pulley. OR The reluctor is 60 teeth, so each tooth is 6°, each rise/fall is 3°. Set MS to 12° and see how may teeth away from TDC you are.

[Evan_VRM]

Regarding timing checks: unless you *know* that your adjustable timing light works flawlessly (assuming you or your tuner are using one), set it to zero or use a non-adjustable light. I spent $100 for a decent one when I got my car back together, set Megasquirt to fixed 10deg advance and set the timing light to match, and the thing was jumping around like +/-5deg between 1000-2000rpm. Once I set the light to zero, set MS fixed timing to zero, I was finally able to dial it in, and my trigger offset ended up exactly at 84deg.

Maybe there are better adjustable lights out there, but I've yet to use one that does what it's supposed to reliably.

I have a non-adjustable timing light, but was going to borrow a programmable one. This may be a stupid question, but will the car run with timing fixed at 0*?

[Evan_VRM]

Well this is all certainly an interesting plot twist... I literally watched him "verify" the timing with a light but obviously there was some confusion as to what he was looking at. Not real confidence inspiring. I will make absolutely damn certain it is dialed in correctly with a light tonight then my tuner and I are going to have a serious discussion.

As for the boost control, AFAIK overly retarded timing will absolutely cause boost control issues. That being said I know creep is an issue with this manifold anyway so I'm not too upset about my configuration now, IF i can get it to make reasonable power.

[mikey.antonakakis]

Regarding timing checks: unless you *know* that your adjustable timing light works flawlessly (assuming you or your tuner are using one), set it to zero or use a non-adjustable light. I spent $100 for a decent one when I got my car back together, set Megasquirt to fixed 10deg advance and set the timing light to match, and the thing was jumping around like +/-5deg between 1000-2000rpm. Once I set the light to zero, set MS fixed timing to zero, I was finally able to dial it in, and my trigger offset ended up exactly at 84deg.

Maybe there are better adjustable lights out there, but I've yet to use one that does what it's supposed to reliably.

[McGyver]

Dumb question: Would having the crank setting and timing completely off contribute to OP's boost control problem using the unmodified WG location?

[ForcedFirebird]

Those numbers are all wrong. You need to use the diag function in TunerStudio to lock the timing and use a timing light. Should be around 84° offset and that's why your timing numbers look so low. Stock timing is in the upper 20's at 100kpa, -1° is already excessive.

[varg]

It’s way off, 84 is the correct number.