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Discussion Starter · #1 ·
I drove my car stock about as long as I could take it - 2000 miles.

After putting on the Spintech Catback about a week ago, I decided to go with a 2.93 pulley (Thanks Injector Dude) and put a Chip in.

This past Friday afternoon, I pulled my car into our shop and let it cool down. While I was waiting on the engine to cool, I unhooked my battery and I pulled the PCM out and cleaned it good. Put the chip in and reassembled my interior. Back under the hood I swapped out the stock plugs in favor of NGK TR6's. After the engine was cool enough for me to touch, I changed out the stock pulley.

After everything was installed, I reconnected the battery and fired the car up. It idled smoothly, I let is run for about 5 mins then took a trip down the road. I drove around a total of about 20 mins, letting the computer relearn. The car drove perfect, drivability was excellent. I finally got the nerve to floor it.... MAN what a difference. All seemed well.

By Saturday night, my car had begun a slight surge, most noticable around 1500-2000 RPMS. As a matter of fact, with the car in neutral and with my holding the RPMS at 2000 you could hear what sounded almost like a miss or something. It sorta popped through the exhaust and the RPMS fluctuate about +/- 200.

Sunday I got up and disconnected the battery, and let the car sit. Then tried driving it again... Same thing. I tried this twice on Sunday actually. No difference.

Yesterday I decide to pull the chip before comming home from work (I reset the computer AGAIN). The car drove perfect, drivability was just like it used to be. So that ruled out something being wrong with my car.

When I got home, I reset the computer, and put the chip back in. What do you know.... car runs great... just like Friday when I first put it in. It ran damn strong actually. I decide to drive uptown and see whats going on. On my way home, I put the car in 4th and ease down on the gas (Did not go WOT), the car made about 9PSI on the stock gauge and I hear AWEFUL detonation..... I backed off and just cruised home. Car is bucking and jerking like an upset donkey, and I'm upset about it.

I don't think the engine is hurt, but I am concerned.

I'm now really anxious to get my Predator in, it should be hear Saturday. Hopefully I have good luck with it.
 

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I've had that...easiest and simplest thing to do is check your plugs...if their white you're running lean...takes no more than 20 min....

Mine did the same...It ran awesome and then the next day it ran bad..checked the plugs they were white...went to a dyno...

16:1 A/F....i was pissed.
 

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I had the exact same problem...I got the chip on Friday..Saturday I raced all night against some friends...Parked it..took it out for a spin on Tuesday...and I got on it slightly and it would choke..I got home let it cool..checked the plugs and sure enough they were all white..I took it the next day to Steeda...and fixed the problem.

The tune i was given was for a 95 C&L MAF and Filter....I had 2.80 Pulley, Exhaust and 12' Filter:rolleyes:

Steeda fixed it...I also gained alot more power....But as far as damage i have none...the car ran stronger than ever...

I have a Lightning and I also encountered the same problems just that it actually burned 2 electrodes off my plugs...I'm lucky no damage occured.

Both situations with the Cobra and Lightning were because of lean conditions...now everything i do i make sure is Dyno-Tuned in front of me...

Check the Plugs...then get it dynoed.

If you dont mind me asking who tuned the chip?
 

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Discussion Starter · #5 · (Edited)
Chris Johnson of JMS

The odd thing is my brother has the exact same setup, only he has a different catback and he has a Densecharger.

The tune is for a 2.93, CAI, and Catback. I still don't have a CAI, so I would think that would cause the car to be rich, not lean.

His car runs perfect and has for several weeks. We do not have a dyno locally, but we are having a dyno day in a few weeks.
 

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Jeez Eric I recommend caution w/chip & untested afr, I'd take the chip out and leave it out and stay out of boost until you can test with a reputable wideband. You've got too much invested to do otherwise.

My 2 beans,
Bill
 

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The Ubiquitous Jimmy V.
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Eric,, Guys run 2.93 Pulleys without a Chip..Do you know what timing is in your chip..?? Mine runs between 21.5 and 22..Some tunes have as much as 25..
I would not keep reseting puter,,because it takes many driving cycles to learn.
I'll bet if you drive it a few hundred miles then nail it your detonation will dissapear..It is common that a chipped pullied car would have tip in detonation until the car had some learn time..
I'd also check the plugs..
Don't rule out that you might have got some poor quality fuel..
 

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Discussion Starter · #9 ·
I can't recall exactly what the timing is at. The way the car is surging down low, it seems as if the car is lean even when not in boost. I'll pull the plugs tommorrow if I get a free chance at work

I actually drove the car a good bit this weekend, I would say at least 200 miles before I reset the computer.

Thanks for the input guys.
 

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Considering I am one of the guys running a 2.93 with no chip, and I don't have the issues you are experiencing (and zero detonation, EGT's read 1400 degrees at the most), I would say your chip has some serious issues. I would get a dyno pull with AF. That was the first thing I did after the pulley. Had to set my mind at ease. I still keep a close eye on EGT's and plugs, just in case. I'd guess that right now, your car is probably safer without the pulley than with it.
 

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Jim,

Although some people can run their cars with a 2.93 pulley and no chip and dont detonate doesnt mean every Cobra can do it..you know what i mean...every Cobra is different.

But i would bet anything you're car is running lean...

The other thing you can do is if you have aTemp. reading gun handy is measure the temp. at each Header...it should be between 1200-1600 deg....I BELIEVE but dont quote me...that anything under 1200 is lean and anything above 1600 is rich...its a trick my buddy taught me...he raced/races cars for a while and is very knowledgable of the Grand Nationals and Regals.
 

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Eric Brooks said:
I agree Bill

I had been planning on PMing you about your wideband. Where did you get it, and how much did it cost.

Have you checked it against the dyno's wideband? How accurate is it.

Thanks
Mine is the Techedge 1.5 that comes from OZland, link here

I've been very happy with it so far, it appears to be accurate based on comparison to dyno sniffers (It reads 3-4 tenths richer than tailpipe, which is expected since it is before the cats and a tailpipe sniffer is after the cats). It uses the same expensive NTK sensor as the Motec and FJO wideband products. If I was doing it again, I would probably get the FJO and display/log data to a Palm device. Check out the FJO stuff here

Bill
 

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I qualify what is safe to run w/o a chip based on your computer code. I have a first run QUD2 computer code vs the later YDH0 and YDH1. 2.93 chip (or even stock) QUD2 cars run 14.5 AFR until about 5000rpm when they go way rich, like < 10.0:1 AFR.

Chris Johnson mentioned to me that the later codes, definitely YDH1 w/ pulley and no chip run 16:1 and sometimes 17:1 AFR below 5000rpm then end up going rich. I would never run a pullied car w/ later code and expect good things to happen.

I had the first 03' Cobra done by Chris. Only problem I had was with the pigtail on the chip, it was picking up RFI interference and would cause the car to miss BAD all at once on hard acceleration and sometimes shut off. He instructed me to cut off the pigtail (6' shielded wire leading to a 4 pack dip switch for the other 3 programs). This defaulted the chip to the program in slot 0 which was all I ran (and have run for the last 6+ months). That eliminated completely the only problem I had with the chip. Still runs perfect. I don't know if that helps but I would definitely give Chris a call.

Jerry
 

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Jerry said:
I qualify what is safe to run w/o a chip based on your computer code. I have a first run QUD2 computer code vs the later YDH0 and YDH1. 2.93 chip (or even stock) QUD2 cars run 14.5 AFR until about 5000rpm when they go way rich, like < 10.0:1 AFR.

Chris Johnson mentioned to me that the later codes, definitely YDH1 w/ pulley and no chip run 16:1 and sometimes 17:1 AFR below 5000rpm then end up going rich. I would never run a pullied car w/ later code and expect good things to happen.
Jerry
Sigh. Not again. This gets on my nerves to the nth degree. Jerry, this is not a personal attack, I understand you are just repeating what you were told, but let me ask a few questions:

1. If you were a tuner who sold tuned chips, and you were asked if a car needed a chip, what would you say?
2. Where are the 16:1 AF dynos? I haven't seen any, for ANY run car without a chip and a 2.93 pulley.
3. How come we haven't heard of a pulley/no chip car going kaboom? If it was REALLY 16:1 below 5K, it would blow into tiny little pieces at 12 lbs of boost, for sure. Come to think of it, the only engine failures I have heard of were due to poorly tuned CHIPS. Kinda interesting, huh?
4. How many tuners do you know of that even dyno a car without a chip? No many, I'd guess.

Here's my take, and instead of speculation, I've actually DONE IT: For almost a year, over 100 passes, 3 clutches, 2 bearing retainers, 4 TOBs, 2 differentials, 3 half-shafts, and going on 20,000 miles now.

My car is a YDH0, 2nd run car. Mods are 2.93, CAI, and no mufflers. Modded pulley, ran six passes on the dyno. My AF? Stoich at 3K, 12.3 at 4K, 11.9 at 5K, 10.4 at 6K, and 10.1 at redline. Here's the graphs:
http://www.svtperformance.com/forums/showthread.php?threadid=22996&highlight=dyno+pulley

The car is fine. Both EGT's read 1400 peak. Plugs (AGSF12FM1's gapped at .038) look perfect. No visible, audible, or other signs of detonation. Ever. None. This includes hot lapping in 103 degree Florida heat.

Look at it this way: If the car is capable for compensating for 87 octane gas at 8 psi (and it is, there are morons who have done this), it is capable of pulling timing to compensate for 12 psi with 93 octane.

I'm not saying some people don't need a chip. I'm not saying that you can't gain by getting a chip (though I am skeptical that I will). I'm not saying that this is the case for every car. But I AM saying that I have never spoken to or read about anyone who has ACTUALLY DONE THIS who got a 16:1 AF ratio for longer than a split second at tip-in. Take what someone who is trying to sell you (or others) something says with a grain or 4,000 of salt.
 

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Discussion Starter · #16 ·
Update!

Good news guys, I found the problem.

My Predator came in today. I already had my JMS Chip pulled out, so I flashed the PCM with the tune for pullied cars.

This Predator is really cool and simple to use. After I flashed it, I took a test drive down the road. I never got on it hard, just easy. I got about 5 PSI of boost, I hear detonation. At this point I am really frustrated. I am thinking something is really screwy with this car. I know this Predator tune is way safe.

I stoped at a service station and reconnected the Predator. I decide to retard the timing as much as it would allow, and also richen up the car as much as it would allow. I then go down the road again, and still have some detonation, but not as bad as before.

Then a light goes off in my head. BAD GAS! I stoped at a Gas Station and fill up my tank. My next cruise down the road, guess what NO DETONATION! The car didn't run real great, not sure what the timing is but it was low, and I had it rich. So then I flash it back to the normal Performance Tune for a Pullied Cobra.... Runs GREAT.

I will say that that JMS program runs better, but it is probably hotter. I'm thinking if I add a little timing it would be pretty compairable.

I feel so much better now. I'll tinker with this Predator some more and keep you guys posted.
 

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Discussion Starter · #18 ·
Yes, the Predator works great. For the price, I don't think you can go wrong. To me the ability to log is the major selling point.

The tune for the Pullied cars is safe. I haven't check the timing yet, but I am going to tonight. Its too hot outside right now.

The car runs ok with the tune, but could run stronger. Actually it may be right for a car with a 2.80 pulley and all the other mods. I have a 2.93 and no CAI yet, so I am assuming my car is richer than it should be.

I did adjust the timing advance up 6% and it made a major difference in the feel. I'll keep tweaking and let you guys know what I find.

I know this thing comes with a safe tune, and the adjustments that you can make are very small. So, someone like me can monkey around and not blow something up. I think a custom tune on this thing will be the ticket.
 

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So basically its Dummy-proof...preventing disastors from happening?

But you could have a tuner send you a custom tune and you could then just upload it on to your ecu without having to send them a chip say..correct?

Sounds neat.
 

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Discussion Starter · #20 ·
Right. If you had a custom tune, I dunno if I would adjust the tune much. But you know Diablo engineers the default tunes REAL safe, because all cars are a little different with similiar but different mods.

To me, $419 is CHEAP.

Look at the price of the Autotap, add the price of a regular chip and you see what I am getting at.
 
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