Help -- Coupla' 930 Tuning/Running Gremlins (long)

[Overpaid Slacker]

So I had a very reputable place tune the Electromotive in the 930. It had a bit of a stumble (very subtle) at around 4k, which was the threshhold where they introduced some ignition retard to keep me from grenading the motor. Not a major problem, but I asked them to smooth out that part of the ignition curve. Bad idea.

Last Friday I picked the car up from the shop after the 2nd adjustment and drove the 930 from LI up to Syracuse. I didn't have time for a shakedown cruise, so I just pointed it NW from LI and headed upstate. It was cold (mid 20's) and the first 1/2 of the trip was on wet roads. So I kept the car at/under 3k for the first 1/2 of the trip to avoid a boost-induced panoramic demonstration of vertical axis rotation.

I stopped before the roads dried out to fill up (I can pass anything on the road but a gas station), and while waiting for the grilf to fill up, I idled for about 15 minutes in the cold -- anybody who knows the Mobil on the Hutch knows you can be there for a while!

An aside -- I think there is an issue with the thermostat. Even when doing some protracted high-speed runs the prior week in ~50 deg, the temp needle never made it out of the lower "box" on the temp gauge. On this trip upstate, it was more than one needle's width under the top of such "box" at the absolute highest. So, I suspect that the oil is continually being fed to (Mr. Moreland's) oil cooler in front of the RF wheel -- ie the thermostat is stuck open.

OK, after idling I pull out of the Mobil and the car fights a bit -- chugs occasionally for the first few minutes. Crap, mighta fouled the plugs... but the chugging goes away in a few miles after running her up to 3k+ a coupla times.

Then, the road dries out, and for the first time I take her up in the revs a bit. Now the weird part... 1st through 3rd gear, she'll pull w/o complaint up to 5k (I didn't take her higher than that). BUT in 4th gear, she'll give me 3350 rpm smooth as buttah, but if I touch 3400, she'll buck and kick back until I'm back under 3300. Coincidentally, 3400 rpm in 4th is almost exactly 80mph indicated.

Naturally, I've got a bunch of questions --
Could I have fouled the plugs, idling this motor for 15 mins in the cold, when the temp gauge read so low? It's a twin-plug motor, putting out about 425 hp.

I'm running pretty cold plugs (motorcycle plugs) b/c in its prior form the motor ran very HOT and it'd been recommended to me to go one stage plug colder for every 50 hp over stock. So, I'm 3 stages colder than stock.

If they were fouled, they shoulda cleaned off w/ some higher-rpm running, no?

Why -- even if the plugs were fouled -- would the car pull OK (not great, but OK) through 5k in 1st-3rd gears but strongly resist 3400+ rpm in 4th? Is some warm-up part of the circuit not shutting off?

The car starts right up w/o protest, idles fine, makes no worrisome noises and doesn't generally complain, except as indicated above.

She's now laid up for the winter, but I want to know wtf could be wrong. Like many other talented mechanics I've dealt with, the guy who did the tuning can figure out how to make anything work -- except a telephone. He hasn't returned calls to discuss the sit. and I thought I'd turn to the Pelicans for some insight.

EDIT -- CHT was about 300 left and 350 right; EGT varied, but was around 1000 (I think).

Thanks in advance.

JP

[304065]

I don't know about the thermostat. You'd have to take it out and put in boiling water to see if it works.

You could have fouled one or more plugs, sure, and the twin-plug would mask the problem. Can you disable one set of plugs with a laptop? Shut one bank off, then the other. You'll know pretty quickly whether you are firing on all six. Or just pull a plug out and look. But if it continued to pull through 5K, I'd say the problem's probably not the plugs, it's the ignition system upstream. Usually when plugs foul that cylinder doesn't fire, leading to a popping sound in exhaust and lots of black smoke out the tailpipe.

So why can you rev it to 5K in I-III but not in IV? I think it's definitely timing-related.

Advance is key to allowing the engine to rev up: when you start the engine, you want the combustion event to occur pretty close to TDC, because at slow piston speeds there's plenty of time for the cylinder to fill and for the combustion event to occur. But as engine speed rises, you have to start the combustion event earlier and earlier in order to have peak cylinder pressure occur just after TDC, when the piston is on the way down. So the system has to dial in advance.

OK, so we've known that since Kettering invented the spark ignition. Now, in the case of a Turbo, because of the higher intake charge temperature, the charge burns faster. So you need to retard the ignition somewhat as boost pressure increases, to avoid having the cylinder pressure peak too soon.

So the electromotive does all that, and dials in ignition retard as boost pressure rises.

Except that at cold engine temperatures (cf. thermostat issue) and low air temperatures (richer mixture) the engine doesn't need as much retard, because the richer mixture burns slower, with a later peak pressure.

The Electromotive has a 3-d advance table, do you know whether the wrench hooked up a temperature sensor? Obviously you don't have "coolant" but maybe there's an input for oil temperature? From the Tec-1 manual:

The TEC also has a single page coolant temperature advance table that allows the advance to be
increased for lower engine temperatures. This corrects for the slower burning, richer cold air-fuel mixture.
This parameter has twelve fixed coolant temperatures from -30 Degrees C to 80 Degrees C.

So in a nutshell, the engine wasn't getting enough advance to rev up smoothly.

But why would this problem manifest itself in IV, instead of I-III? The only possible answer is that the aerodynamic drag is greater at 80 MPH than it is at lower speeds. It takes more power to accelerate the same mass at 80 mph than it does at 60 mph, because of the effect of aero drag. But without enough ignition advance, it wasn't possible to accelerate smoothly under that kind of load. Higher cylinder pressures would help somewhat (with a greater engine load, the piston doesn't want to move out of the way as easily, resulting in higher cylinder pressure, which tends to DECREASE the advance requirement as a higher-pressure mixture burns FASTER) but not enough.

Either that, or there's some strange jog in the advance values in the table.

Time to get out your laptop I think.

Good luck!

[Overpaid Slacker]

I agree w/ the aero. drag bit -- it's all I could think of as well. I'll check to see if there's a temp. sender hooked up to the e-motive. The car definitely ran better earlier in the evening when it was warmer than after dark (and further north) where the temperatures were 10-15 deg. lower. If my thermostat was working, the motor would've been less susceptible to temp. fluctuations and better able to maintain a constant operating temp despite atmospheric temps dropping.

Sigh. Well, it'll be next spring before I need to worry about this again, but then I've got to get the car from the 'Cuse to LI again.

Screw cars. I'm gonna collect Beanie Babies or some no-maintenance ***** from now on.

JP

[Amac]

JP,
Does'nt sound like a fouled plug is your problem.
One fouled plug is hard to detect with a twin setup.
I think your tuner friend may have adjusted the timing
a little too far.
If you fouled both plugs in one cyl. you would feel a vibration
and throttle response would suck.
A turbo on 5 cyl's sounds like farm tractor.

[RoninLB]

disclamer: I know nothing about Electromotive or turbo tuning.


It had a bit of a stumble at around 4k, which was the threshhold where they introduced some ignition retard
------ Uh Oh, assuming this condition is at cruise.
The engine should be able to tolerate much greater advance at cruise than at acceleration. ie: a real vacuum advance, not our routine 911 Bosch vac dizzy mechanics, senses greater vac and advances the ignition at cruise. Upon acceleration the vac crashes and this advance leaves the circuit. Greater advance at cruise gives a more efficent combustion and better gas millage.

I idled for about 15 minutes in the cold -- -- chugs occasionally for the first few minutes. Crap, mighta fouled the plugs... but the chugging goes away in a few miles after running her up to 3k+ a coupla times.
-------- very cold plugs, extremely rich mix, very low advance or a combo. A slow acceleration fired the wet plugs. A rapid acceleration crashes EGT & coats the wet plugs with carbon 'cause of inefficent "drying" of the wet plugs. This situation only ruins the plugs if not fixed.


the temp needle never made it out of the lower "box" on the temp gauge.
------ I believe the top edge of the lower "box" is 178deg. A pelicanhead answered this needle position a couple of weeks ago. 170-180deg oil temp is a beauty to behold imo.


1st through 3rd gear, she'll pull w/o complaint up to 5k BUT in 4th gear, she'll give me 3350 rpm smooth. I touch 3400, she'll buck and kick back until I'm back under 3300.
------ read cruise ign timing above. The Peter Principal relates to engine load. ie: cruise ignition sucks

Could I have fouled the plugs, idling this motor for 15 mins in the cold, ?
------ The plugs became fuel wet from a rich mix or retarded ignition disturbing the air/fuel/ignition combo necessary for efficent combustion.

I'm running pretty cold plugs. If they were fouled, they shoulda cleaned off w/ some higher-rpm running, no?
----- depends if the plugs were in the early or late stages of detoriation & the technique for "cleaned off"

Why would the car pull OK through 5k in 1st-3rd gears but strongly resist 3400+ rpm in 4th?
----- greater engine load and improper timing or fuel feed or combo. although based on what my eyes see so far your ignition sucks.


CHT was about 300 left and 350 right
------ somethings wrong 2X. Without boost/ at cruise CHT should be lower than 300 imo.. Perhaps lousy ignition scrambled the heat boundary layer between combustion and chamber internals.

EGT varied, but was around 1000 (I think).
------ That's absurd imo.
Excessive fuel, extremely retarded ignition, or an air feed reduction. Based on all of above your ignition curve sucks. Your cruise EGT should be vary between 1,200-1,350 in 5th above 3.2k rpm depending on road conditions imo. In 4th add 50-100deg. You should tune your engine to a max EGT possible within the CHT envelope.. obviously 1,500deg will skyrocket your CHTs.

The car definitely ran better earlier in the evening when it was warmer than after dark where the temperatures were 10-15 deg. lower
----- colder ambiant contributed to a richer fuel mix that magnified your $hitty ignition timing problem imo.

overall this should be an easy fix

[David]

My EFI 930 project is still in the works so I'm a real novice to this, but I noticed some of multi coil ignitions call for a small plug gap. If you have too large a plug gap the ignition may have trouble at higher rpm under load. Just a thought.

You should try the Turbo911 site. There are several people there that are very familar with EFI.

[beepbeep]

Hmm, It might be good if you explain the details. What exactly is done to your car? Which mods?

Still running CIS? Twin plug? Dizzy/direct fire? Mappable ignition curve?

[RoninLB]

Originally posted by john_cramer

I'd say the problem's probably not the plugs, it's the ignition system upstream.

So the electromotive does all that, and dials in ignition retard as boost pressure rises.

So in a nutshell, the engine wasn't getting enough advance to rev up smoothly.

Time to get out your laptop I think.

Hey cramer..
do you know anything about operating the Electromotive flavor 1 programing? Want to figure this thing out?

Huh

[304065]

Ron,

I don't know nothin' 'bout nothin'.

If the gentleman's vehicle were more conveniently located, than, say, Hudson Bay, I could be persuaded to fire up my OWN laptop, get the software, and have a look at the ignition maps. Might even snap a few cool ones along the way.

I propose that we revisit the issue come springtime.

[Overpaid Slacker]

Kos -
Yeah, springtime is the time at this point.

Goran -
3.3 liter, CIS, Electromotive TEC-1, crankfire (Clewett), twin-plugged, recent top-end overhaul, HAL meter, dual CHT, EGT. Just completed engine swap from wrecked car to "new" 1979.

The TEC-1 is "primitive" by TEC-3 standards, but it's fully mappable ignition. I don't have the knock sensor hooked up b/c the exhaust is so aggressive it kept setting it off.

I'm assuming it's ignition map issues, as the same car ran much better before re-mapping, but I thought I'd solicit Pelican input as I know less than "nothin' 'bout nothin'".

Thanks for looking.

JP

[304065]

I forget, did you ever put in that Kokeln turbocharger?

I spent a few minutes with the TEC-1 manual last night, for an "old" system it's pretty darn sophisticated. It will also control the fuel. . .Mwahahahaha!

[Overpaid Slacker]

Yeah... it'll run fuel, but that's a future upgrade... when I decide I need to go faster still.

I didn't put in a Kokeln t/c, Stephen @ Imagine Auto strongly recommended the K27 7200 for me, given how I intend to use the car. I also added a TiAL wastegate and Blitz EBC.

JP

[RoninLB]

Originally posted by john_cramer

I could be persuaded to fire up my OWN laptop, get the software, and have a look at the ignition maps. Might even snap a few cool ones along the way.

I propose we vote on your nomination as Management Director.

[304065]

You may want to consider the LM-1 data logger as an upgrade for the HAL meter. The HAL uses an old-school narrowband sensor and attempts to interpolate to show AFR, whereas the LM-1 uses a true wideband sensor, and will drive an in-dash display.

Ron, I suppose as Managing Director one of my first responsibilities will be to buy everyone a round of brewskies.

[RoninLB]

Originally posted by john_cramer
Ron, I suppose as Managing Director one of my first responsibilities will be to buy everyone a round of brewskies.

sure boss.. just say when.

[Overpaid Slacker]

There are not two guys with whom I would be more comfortable entrusting Die Rakete than Kos and Ron.

Maybe what I oughta do is drive down to the hangar sometime this spring and we can do what we gotta do. I don't think it's rocket surgery, I just think that this particular mechanic ... um ... overstated his Electromotive competence.

I'll pick up an LM-1 as well prior to our undertaking... though it doesn't look as cool as the HAL Meter, with its sweet LEDs and all...

JP

[304065]

The LM-1 will drive an external display, which looks like this:



Link: http://www.innovatemotorsports.com/products/xd1.php

Above image: Copyright © 2004 Innovate! Technology, Inc. All Rights Reserved.

The LM-1 will also drive external analog meters. . . one could have NH or PA Speedometer put an AFR scale on one element of the "triple gauge" . . .

[Overpaid Slacker]

Sweet -- all I'd come across at Innovate's website was the analog.

JP

[RoninLB]

there is also a fuel problem going on I believe.