How did you mount the FM heat shield? Can't get mine to fit properly with my MKturbo setup

 

the forward leading edge of the head shield that's been folded down clashed about 5mm. I hit it with a grinder to make some reliefs, but it still buzzed in some conditions. I ended up massaging it with the biggest pair of channel locks I've ever seen while we were on the dyno until it didn't buzz under WOT.

 

Weekend project. Hopefully this is why I stalled twice...

 

I've been fighting an intermittent stall/no start condition, and it's been getting progressively worse. The first time it happened, it died after driving for about 20 minutes. The next time, about 10 minutes. Then about 5 minutes. I just tried to start it, and it fired up and ran for about 5 seconds. It won't start again after stalling until some time has passed. Every time it's died I was either idling or cruising along at about 3k.

At first I thought it was fuel, but now it has a new pump and relay. Fuel smell from tail pipe after cranking is evident. I've logged it during no-start, and I'm getting cam and crank signal. Sync error count isn't going nuts. When it dies, all the electrical appears to be still working. The pump primes, the starter cranks... I just don't get anything. It doesn't cough or sputter, it just stops running. Main relay looks healthy just based on visual inspection. The one oddball symptom I noticed is that the battery voltage reported by TS was off by a solid .5v from the battery as read by a multimeter. I corrected for it with the calibration tool, but I don't recall ever seeing that before.

I'm stumped. It's gonna be a slog with a multimeter I think. I'm open to any advice.

 

Just a quick recap: spent a month with an undiagnosed stall issue. Ultimately, it appears to have been a loose butt splice on the spark coil ground. Curly pointed out that a misfire is evident in one of my stall events that I logged, and you can see it here as a jiggle in the RPM's right before it stalls.

Anyway, the car seems stable again, so I'll be grinding away at the miles to break in the clutch. 900 miles to go until I can has trubo again...

 

Happy to help, glad it's working again. I forget what crazy bad misfire issue I was having when I first started to recognize what they looked like on an RPM trace long ago, it's certainly helped diag issues more quickly. Basically an engine should make a smooth curve up and down, never sharp angles like what showed in your log.

 

I'm slooooowly getting more familiar with tuning. IDK why, but I never completely 100% zero'd out my MAT correction, and it's played hell on my VE tuning. Even a 5-10% correction seems to have been making my tune run too rich in colder temps and too lean in the heat. I usually tune on my commute, and the ~25* temp swing from AM to PM just made tuning feel kind of worthless. I was also getting slowly climbing AFR's during hot idle scenarios, and bad heat soaked lean hot starts. So! MAT is zeroed out to 100% across the board, and we start again with the VE tuning.

I understand that I should avoid using MAT correction to bandaid lean hot starts, so I'm looking for... another bandaid for that? AIT is in the correct location (fwd facing on cold side collector of the IC).

 

I make sure ASE % and ASE taper are fairly high above 180*. It kinda sucks cause you want a 3rd variable, which is how long the engines been sitting since it last ran. If it's been a few seconds, you can restart with nearly zero ASE and be fine. If it's been 5-15 minutes, you'll need a **** ton to keep it from stalling. If it's been 1-2hr+, you can just rely on cooler temperature settings on your ASE to properly start it. But I'd rather have it idle rich when it's a more immediate restart than stall out after a small delay like getting gas, grocery shopping, etc.

I look at 3 gauges. EGO correction, ASE %, and AFR. I watch ASE taper off, making sure the AFRs are both in a decent range and that the engine isn't trying to stall, so it'll vary per setup. Right as ASE nears 0, I want EGO to take over and be able to stabilize idle to ~14.7 (or whatever your engine likes to idle at). There's a "ego delay after start" timer you can increase or decrease to make sure EGO takes over at the right time.

 

Yeah, that's kind of the direction I'm heading in my understanding. I'm going to go for the ol' "U" shaped ASE taper to hit ~1k+ cycles at hotter coolant temps. I guess I'll want to do something a bit similar with the ASE %. I know it's especially bad right now because I have EGO correction off for tuning.

That brings me to another question: Do I actually need to turn EGO correction off for VE tuning? I see conflicting opinions. I'da thunk that VEAL would automatically work around it...

 

OK, so we have hot start issues due to injector heat soak.
It looks like 96-97 NAs have an OEM work around for this: The PRC solenoid shuts off vac reference to the FPR for a bit (~1min?) at start.
What if you glued or clipped on a little thermistor on to an injector, plumbed in a PRC style solenoid, and set it up as a programmable input in TS so that you can block vac to FPR based on actual injector temp? IIRC, you can set up programmable inputs with a timer, although I can't remember if you can set it as seconds or cycles or either. This would eliminate the need for bandaiding it with ASE % & ASE taper. It would only give you more fuel when you actually had heat soaked injectors. I guess the only unknown would be how much extra fuel you'd get by blocking the vac signal to the FPR. Thermistors and vac solenoid valves are pretty cheap.

Just armchairing here. Could be an interesting little science project.

 

I broke down and bought a set of the Gen 5 Paco hub stands. Alignment is:
front camber -2.5
Front caster ~3.5 (3/4 wheel turn with no weight factor)
Front toe 0
Rear camber -2
Rear total toe 1/16" in

It's really easy to get at everything. Don't know yet how accurate and repeatable the alignment will prove to be.

 

I was fighting erratic unstable hot idle. Some time spent contemplating my logs revealed that I was getting a hot idle TPS .1% above my cl idle threshold. Hopefully a little extra slack in the throttle cable clears it up.

 

Can you adjust the CL idle threshold a little?

 

Yeah, of course. I just noticed that it was .3% at cold idle, and .9% at hot idle, which made me think it was the throttle cable running out of slack as everything heat soaked. I currently have the threshold at .8%. If adjusting the cable doesn't solve it, I can either adjust up my cl threshold, or maybe adjust the tps calibration.

 

 

Easy enough

 

I was on my phone, sorry for the brief response. .6% is like the difference in resistance going from cold to hot, probably not your cable stretching. Therefore, in order to decrease that change, you need to depin your TPS, and crimp on a single strand of mil-spec wiring from the sensor to ECU, taking the shortest path possible to reduce as much effect from the heat as possible.

Or change it to 1%.

 

Hahaha nice. That's what I call an "aerospace no". As in: "you could, but you shouldn't. Because stupid."

 

Man, I suck at tuning. I can't figure out what's going on with my CLI. It looks like it is oscillating too much, and can never enter CLI? Here's what I'm working with:

 

If you put it in open loop/warmup mode, does it start at 1500rpms when cold and settle to your target idle when warm, with AFRs starting at ~12.5 when cold and ending at ~14.5? If not, make that happen first. Rather than trying to get CL, idle ve, fuel table, ignition table, and initial value table right all at once.