Unichip, Supercharger and "check engine light"....

Busa196 · 02-08-2008, 07:07 AM

I’ve got an ’08 Wrangler with 2k miles and the Hesco blower on it. Originally I didn’t have the Unichip and the Jeep ran fine with the exception of the TPS light coming on every now and then. I bought the Unichip last week to help with the TPS light problem ( I was told it would "help" but probably not eliminate the problem) and to aid in drivability in the lower RPM range (additional timing).

I installed the chip last night and drove 32 miles to work this morning and noticed 2 things- the check engine light is now on and the Jeep “surges” a little while on cruise control between 65-75mph…..almost like it can’t decide where it needs to be. Other than that, it runs fine- no issues. I originally thought the PCM needed to re-learn the new program and that after a few miles the check engine light would go off?? Guess not. Any ideas?

-Busa196-

**ChicagoGuy** · 02-08-2008, 10:11 AM

I've not used your particular combo (Hesco and Unichip), but don't run a chip with a blower unless the chip is made explicitly for that setup. Unless they are programmable, all they really do is change the timing.

If you are getting a check engine with a supercharger, you are likely a few moments away from detonation. What compression ration are you running? How much boost? I've been working superchargers on Chevy engines for years, and I can tell you that a CE light in a siutation like this is usually a misfire, and if that engine leans out...BOOM!

But I'm paranoid. I also think chips are typically crap. I had a JET in my ZJ, but when I went full bore with headers, hi-flow cats, new exhaust, I ran BETTER without the JET chip than with. If there are other less doom and gloom scenarios for this situation, I'm drawing a blank, but I'm sure someone else will point out the error of my ways.

Pull the chip.

Busa196 · 02-08-2008, 10:31 AM

Quote:

Originally Posted by VetteDriver

I've not used your particular combo (Hesco and Unichip), but don't run a chip with a blower unless the chip is made explicitly for that setup. Unless they are programmable, all they really do is change the timing.

If you are getting a check engine with a supercharger, you are likely a few moments away from detonation. What compression ration are you running? How much boost? I've been working superchargers on Chevy engines for years, and I can tell you that a CE light in a siutation like this is usually a misfire, and if that engine leans out...BOOM!

But I'm paranoid. I also think chips are typically crap. I had a JET in my ZJ, but when I went full bore with headers, hi-flow cats, new exhaust, I ran BETTER without the JET chip than with. If there are other less doom and gloom scenarios for this situation, I'm drawing a blank, but I'm sure someone else will point out the error of my ways.

Pull the chip.

Thanks for the comments, well noted. The motor is completely stock, and i'm only running 5-6psi. The chip is indeed specific to a blown application with a few other parameters. The light has been on since I first started it with the chip and it sat at idle.....ie, it didn't come on after I was under boost. After speaking with Hesco it appears as if this is "normal" for the first 100-150 miles- then, the computer will re-learn this new chip and the light will go out. I'm not real keen on pulling out a $586 dollar chip after 20 min of use. We'll see.

I've been talking to Hesco a lot the past 2 weeks and it seems as if the kit hasn't been out long enough (they told me they've sold 50 units) to log any significant amount of historical problems, codes, etc......at least that's the impression I get when I'm on the phone with them. There's a lot of "maybe, probably, could be, sometimes," etc.... and not a lot of "yes, no, definitely not, this is why, here's how to fix it," etc......

Are you a member of CorvetteForum? Assume you are- I've got a blown C6 as well and I'm an avid member of that forum.....primarily in the FI section

Jason

BigJerm · 02-08-2008, 10:57 AM

did they ever say why its normal that the computer has to "learn"? Ive had boosted cars and help install many superchargers and turbo kits and getting a CEL was never a normal situation tunned or not. Im just curious about their reasonings

**ChicagoGuy** · 02-08-2008, 12:08 PM

Yeah, I'm in C4 FI a fair amount as well. A blown C6? Very cool...

Maybe I should put my motor in the JK -

If the programming is set up for the s/c, then I'd ask more on what was happeneing when the CEL came on. Were you cruising at speed or accelerating up to 75 - i.e. what RPMs when the light came on? I could see the stock ECM reading the delta from the chip's parameters vs. before as an emissions failure.

As for the learning part, know it happens, don't know "how".

TheGillz · 02-08-2008, 12:12 PM

Quote:

Originally Posted by Busa196

The light has been on since I first started it with the chip and it sat at idle.....ie, it didn't come on after I was under boost.

................................

nota4re · 02-08-2008, 12:40 PM

Do yourself a favor and pull the code for the CEL and see what it is. From there, many people can likely help you with the diagnosis.

The "learning" from a chip install is rubbish in 99% of the cases. The only thing that the ECU is going to update with time is fuel trim values. This will help the ECU to arrive at the target a/f ratio more quickly. Consider the fuel trims a "correction factor". The reason that they are there in the first place is so that the ECU can correctly run the egine over it's lifespan.

Pull the codes and report back. After the code(s) are pulled, the same device can usually reset the CEL. Depending on the severity of the CEL, some require a physical reset with the tool. Other codes will reset themelves after they have a pre-programmed number of in-spec inputs.

Busa196 · 02-08-2008, 01:52 PM

Ok. I definitely need to pull the code and find out what it is.....I'm new to the "new" Jeep scene....can I cycle the ignition off/on 3 times to pull the code???.......or do I need to go visit the Harvard grads at my local O'Reilly's

thundercat900 · 02-10-2008, 11:21 AM

I would pull the code and then clear it.
Are you running the A map or the B map.
With automatics I would recomend running the "A" map, The "B" map is more agressive and has set lights on automatics, it is just a sensor issue between the crank sensor and the unichip adjusting the timing. The 6 speed jeeps have a much stronger crank sensor signal and don't set the light.

Let me know what code it set and give me a call at the shop. Other than the light it run's good doesn't it?

Jon

thundercat900 · 02-10-2008, 11:23 AM

Quote:

Originally Posted by Busa196

Ok. I definitely need to pull the code and find out what it is.....I'm new to the "new" Jeep scene....can I cycle the ignition off/on 3 times to pull the code???.......or do I need to go visit the Harvard grads at my local O'Reilly's

Stop by an Autozone or O'Reilly's etc... and have them pull and clear the code. You may have to have the key on and the engine off to clear the code.

Busa196 · 02-11-2008, 08:30 AM

Didn't have time this weekend Jon- I'll bring it buy Autozone tonight afterwork and let you know what code it is.

As far as it running better, it's hard to tell as I'm a bit reluctant to pedal the Jeep enough to make any kind of significant boost with a "check engine" light on. I've been babying it.

As stated above the Jeep also "surges" on cruise control now....a constant back and forth of the seat can be felt. This has remained unchanged and the Jeep has been driven over 200 miles with the chip now.

My setting is on just as you suggested- the A map.

-Busa196-

adaycj · 02-11-2008, 08:52 PM

Quote:

Originally Posted by thundercat900

The 6 speed jeeps have a much stronger crank sensor signal and don't set the light.

Let me know what code it set and give me a call at the shop. Other than the light it run's good doesn't it?

Jon

My service information lists exactly the same crank position sensor despite the transmissions. Please explain.

I would also be reluctant to put my foot into it with an unexplained CEL. As stated before, if the light is on for an emissions code (evap for example) then no big deal. If has legitimate engine codes, then it needs to be fixed. Really it needs to be fixed anyway, because if you have a failure you will never know if the CEL is already on.

The wandering/hesitation symptom you describe matches a lean condition which gives me the same "horror story" feeling as VetteDriver. Danger Danger.

Busa196 · 02-11-2008, 09:30 PM

Quote:

Originally Posted by adaycj

The wandering/hesitation symptom you describe matches a lean condition which gives me the same "horror story" feeling as VetteDriver. Danger Danger.

Agreed- hence the reason I've been extremely easy on the Jeep. But, it only hesitates on cruise control- when using the pedal to maintain the same speed, it's fine. I went to "Advanced" Auto Parts tonight to get the code....."Bubba", was unable to get me the code because his software "needed to be updated.".....real "Advanced", eh?? Sweet.

Every single time I go to an autopart store, it's a disaster....no matter what I'm there for. I almost hate going to them as much as I hate going to the dentist. For the most part, if it's not in the computer, they have no clue what you're talking about. Ok, rant over

I'll try somewhere else tomorrow.

thundercat900 · 02-12-2008, 06:58 AM

Quote:

Originally Posted by adaycj

My service information lists exactly the same crank position sensor despite the transmissions. Please explain.

I would also be reluctant to put my foot into it with an unexplained CEL. As stated before, if the light is on for an emissions code (evap for example) then no big deal. If has legitimate engine codes, then it needs to be fixed. Really it needs to be fixed anyway, because if you have a failure you will never know if the CEL is already on.

The wandering/hesitation symptom you describe matches a lean condition which gives me the same "horror story" feeling as VetteDriver. Danger Danger.

Both use the same sensor but one is reading off of a flexplate and the other is from a thicker flywheel. The output is weaker on the auto's.

As far as the cruise control surging, we have had a few guys tell us about that. its not from the unichp as it does it without also. We are working on a fix. It has to do with the factory calibrations for cruise control...ie map voltage vs TPS which has been changed with the addition of a supercharger.

Busa196 · 02-12-2008, 06:12 PM

Ok, had my shop pull the codes today- all were "historical" and none were current. After he cleared them he started it and the CE light was off and remained off, but the Jeep was only idling- I haven't driven it yet to see if they would stay off. Any thoughts on how the chip might cause the below codes?

Supercharger only= no CE light and no codes. I installed the Unichip and immediately got a CE light with the following codes;

P0131 ‐ O2 Sensor 1/1 Circuit Low
P0137 ‐ O2 Sensor 1/2 Circuit Low
P0138 ‐ O2 Sensor 1/2 Circuit High
P0157 ‐ O2 Sensor 2/2 Circuit Low
P0151 ‐ O2 Sensor 2/1 Circuit Low

-Busa196-