Supercharged 1UZ Bangkok Drag Truck

PARTS FOR SALE: Send an email to [email protected] for availability.

After a big rain ended, and after I finished up some last minute "small jobs" on the race truck, and after the strip dried a little, I made a few test blasts on the return road of Bangkok Drag Avenue. Unfortunately the strip had closed by the time I was ready. There was nobody around to record the actual test runs, but I can tell you; it romped and stomped! Go here for the YouTube of the engine running.
 
"I'm going to need rat poison if I am going to drag race in Thailand!


I had a two hour window at the drag strip before it rained: fuel, oil, trans
fluid - check. Turn on the power and put some heat in it - what's this? . . .
fans coming on and off, lights flickering . . . . what the . . .? Oh
Droppings! Rats, the mice ate the wiring! AGAIN! I'm going to need rat
poison if I am going to drag race in Thailand! There was an actual nest
inside
the dash. I did not reach in to clean it out: this is Thailand -- there
are vipers and cobras here that follow mice to their nests and then take a
nap after their snack. Time to call the electrician. Oh well.
 

JustenGT8

New Member
LOL well not really, but after all the issues you have had? :) poor bugger, lucky you didn't have a shotgun handy or i can imagine you may have ventilated your car a bit more than it needs ;)
 

XR8tt

Moderator
Aha we're obviously car NUTS !!!

That loom looks like it could easy be fixed as you can see where the wires go or come from...
Check there's nothing catching on wires!! ???
Had a REAL bad experience at a track day when loom decided to wrap
itself around steering shaft !!!
Not being able to turn steering and getting your foot burnt at the same time
due to short, is life shortening !!!
 
I have consulted several important scientists on the subject of "keeping mice out of your race car" and have been given a sure-fire method: peppermint oil and Downey Dryer Sheets distributed here and there throughout the aforementioned race car. I will put this unexpected and fascinating method of rodent aversion therapy (RAT) to the test this evening when I visit my shop with the electrician. Stay tuned for the data set.
 
Got the wiring fixed. The rodent aversion therapy (RAT) worked: no more wire biters. Motor starts and runs very snapily. But the frickin' weather will not cooperate! Will it ever stop raining? I will try next week-end . . . . again. :mad:
 
Well, the "RAT" therapy worked! No more rat-eaten wiring! And, more importantly, NO RAIN last night (after six successive week-ends of rain!). So, my tuner buddie and his crew from VooDoo Racing in Pattaya, Thailand headed for the track, Bangkok Drag Avenue. We first swapped out the -8 fuel lines and filter from the tank to the fuel pump with all new -10 fittings. Nice. Then we started it up and worked on the cold start-up mapping and the off-idle mapping. But . . . we thought we heard an intermittent miss. After checking the coils and plug wires (leads) we had all eight. Time for a test blast. Oh no . . . now it is hitting on only six or seven cylinders. Back to the shop . . . checking coil insulation . . . wrapped all the plug wires with insulation so no voltage leaks. Then another test blast . . . Oh No! . . . now only six cylinders. After checcking the plugs, we found #1 not firing, so also checked #6, as it uses the same coil (lost spark). Sure enough, #6 not firing either. More consternation and checking. Tried to start it again . . . no spark. A quick check of the AEM showed all was well . . . but the ignitors, between the MSD CDI were smoldering . . . the 2JZ (I use 4 of 6) ignitors had failed. A check around the pits with 2JZ racers revealed they didn't use ignitors with their 2JZs with CDIs and coil packs, so none available. We called it a night. See video link below for the test blasts.

http://www.youtube.com/watch?v=cU0NDUTfG3s&feature=player_embedded

On another note, perhaps the readership of this forum can help answer a question for me. Why run ignitors with a CDI anyway? The MSD installation instruction (the new DIS-4) shows diagrams for both with and without ignitors. Some say the ignitors "protect" the coils, others say you do not need them at all, since there is a "no dwell" in the CDI anyway, and coils fail for other reasons, unrelated to whether or not there are ignitors. What say you?

Of course, now I will be away from Thailand for the next three (3) weeks. Oh well.
 

cribbj

"Supra" Moderator
Staff member
Jeff, how about some more details of your ignition setup? A block diagram showing the major components would be helpful.

I would think trying to run external ignitors in any CDI setup would be a dangerous thing to do. They're used only in inductive ignitions to switch on/off the fairly large charging currents to the coils as signaled by the logic level outputs from the ECU. External ignitors are really just solid state relays, with some built in overcurrent/current limiting.

MSD, AEM and other CDI manufacturers have adapted their CDI boxes, so they "can" run between an ECU equipped with internal ignitors (usually an OEM type ECU such as Motronics, etc.) and the coils, but if your ECU has no onboard ignitors (and I'm 90% sure your AEM does not), then there's certainly no reason to add external ignitors if you want to run CDI. Any good CDI box should be capable of accepting a logic level ignition signal from an ECU.

With a CDI type ignition, all the charging and energy storage is done in the capacitors of the CDI box, then the CDI box sends that charge directly to the coil in one high voltage blast (usually around 400-500v). The coil then transforms that high primary voltage by its turns ratio (usually 70:1 up to 100:1) to the secondary voltage

Ignitors aren't meant to handle high voltage, only high current, so it's no wonder yours let the smoke out if they were between the CDI box and the coils. If they were wired between the ECU and the CDI box, in order to do a signal inversion, frankly I don't think that's necessary, because as I mentioned above, any good CDI box these days should be able to accept a logic level ignition signal from an ECU.

Another point to be very careful of, is to be sure that your coils are compatible with, and recommended for your MSD ignition. Many make the mistake of trying to use big coils with a lot of inductance on a CDI system, and subsequently smoke the coils, and/or the CDI box. You must always remember on a CDI system, the coils are only used as voltage transformers, not for energy storage.

Here's an excellent description of the CDI vs Inductive coil differences from McLaren, who build both types:
http://www.mclarenelectronics.com/Products/All/App_Act_Ign.asp
 
Thanks cribbj. The ignitors are between the AEM ECU and the MSD CDI, as recommended by AEM. I should have stated that. I am using the 2JZ ignitor pack but only using four of the six ignitors. I am told, "They [ignitors] fail sometimes." Maybe there is an AEM specialist out there who can answer the question, "Can a signal go directly from the AEM to the CDI without the ignitors, if configured correctly. And if so, how do you configure the ECU for this kind of set-up." Your input has been, and will be appreciated.
 

cribbj

"Supra" Moderator
Staff member
OK, so the ignitors are in there to do a signal inversion. I thought MSD's boxes could take either a classic ignition (ignitor based) input, or a logic based one directly from the ECU, but I could be wrong.

I know that AEM's CDI ignition can take both, and I'm pretty sure M&W's system can take both.

You may hear ignition people talking about rising edge signals and falling edge signals for ignitions, and here's a quickie explanation:

The classic (ignitor) based signal is a falling edge (pull to ground) to start the coil charging then it's a rising edge (open the circuit) to trigger the firing event. Consequently it's referred to as a "rising edge trigger"

An ECU puts out a 5v logic signal or sometimes a 12v switched signal which is a rising edge to start the coil charging, with a falling edge to trigger the firing. This is referred to as a "falling edge trigger".

If your MSD needs to see the classic rising edge trigger signal at its input, then the AEM's ignition signal must be inverted, and using ignitors is a cheap way of doing this. However, if I remember correctly, the 2JZ's ignitors are somewhat special, and don't like a true 0v and 5v signal at their input. I can't remember the details, but I recall that getting these ignitors to play well with the AEM in the early days was a challenge. The 2JZ-GTE was one of the earliest engines to have COP's and I don't think Toyota's ignitor technology was fully developed at the time. Perhaps pullup resistors were required to make the ignitor happy, or something similar.
 
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