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Discussion Starter #1
I was recently told by Jim at Halltech that the T-1 alone will cause the stock undersized injectors to work at 95% duty cycle. Will this cause a lean condition and/or cause for concern?
 

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I'm surprised that Mr. Halltech didn't give you more info besides the problem it might cause. Didn't he say anything about the "cure", or what the detrimental effects would be?
 

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Discussion Starter #5
Mr. Halltech sent me this:

The stock 2002 Z06 injectors were sized down and are way too small for any mods. They run at 95% duty cycle with our intake. By changing to our 310cc/min RC Injectors, the Long Term Fuel trims are returned to baseline, which dials in WOT very close to perfect. Without the injectors and ported throttle body and AFR, we made 367 RWHP with just the intake alone. The additional 30.2 RWHP was with our complete T-1 Package.
O.K., I don't want to run lean, if that's what this means? And what does all this other stuff cost? Is it still " the deal of the century"??
 

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Here it is guys

Try this:

http://www.z06vette.com/forums/showthread.php?s=&threadid=9510

Read my posts on fuel trims, injectors etc. in the below thread. Hope you learn some stuff.

http://www.z06vette.com/forums/showthread.php?s=&threadid=9468

Here is the item that may answer your questions, but I suggest you read the entire thread.

Originally posted by 2002blackZ06
Jim, could you please explain this question in laymens terms. Very basic. I have a 2002 Z06 stock. I put your T-1 sidewinder on. Am I going to have lean or rich issues. Where I live, we don't have any real Corvette tuners to work these problems out. This is one of the reasons I bought your system. I was lead to believe that it was plug and play so to speak. Bolt it on and enjoy. Put her on and drive her!!!! etc.
Thanks
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We have over 100 T-1 Intakes sold, with maybe three that have reported the code. It can be reset from the driver's seat in 1 minute, and so far they have not returned.

You should have the same 16 RWHP we got, with no other changes to your Z06. We never saw a lean code, and have only heard of two customers getting them. The idle relearn process described in our instructions, usually solves the code problem since that procedure resets the butterfly position of the throttle body.

You will never see a rich code, but if you do, it will not be the result of our T-1 intake.

All of the other mods we have added were intended to maximize the performance of our intake.

GM took the screen out of the MAF this year. That one event is the culprit behind all of these issues with the aftermarket.

We NEVER heard of one code last year with our TRIC and the 01s, unless someone decided to pop out the laminar screen in the stock MAF or go to the Granatelli unit.

The workaround is simple in its application, and my question to you is, have you gotten a code? It will occur within the first 50 miles if at all. If not, don't worry about it. This post is to explain everthing we have learned about the 2002 trims.


Jim
 
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Re: Here it is guys

fyrcaptain said:
Try this:

http://www.z06vette.com/forums/showthread.php?s=&threadid=9510

Read my posts on fuel trims, injectors etc. in the below thread. Hope you learn some stuff.

http://www.z06vette.com/forums/showthread.php?s=&threadid=9468

Here is the item that may answer your questions, but I suggest you read the entire thread.

Originally posted by 2002blackZ06
Jim, could you please explain this question in laymens terms. Very basic. I have a 2002 Z06 stock. I put your T-1 sidewinder on. Am I going to have lean or rich issues. Where I live, we don't have any real Corvette tuners to work these problems out. This is one of the reasons I bought your system. I was lead to believe that it was plug and play so to speak. Bolt it on and enjoy. Put her on and drive her!!!! etc.
Thanks
--------------------------------------------------------------------------------



We have over 100 T-1 Intakes sold, with maybe three that have reported the code. It can be reset from the driver's seat in 1 minute, and so far they have not returned.

You should have the same 16 RWHP we got, with no other changes to your Z06. We never saw a lean code, and have only heard of two customers getting them. The idle relearn process described in our instructions, usually solves the code problem since that procedure resets the butterfly position of the throttle body.

You will never see a rich code, but if you do, it will not be the result of our T-1 intake.

All of the other mods we have added were intended to maximize the performance of our intake.

GM took the screen out of the MAF this year. That one event is the culprit behind all of these issues with the aftermarket.

We NEVER heard of one code last year with our TRIC and the 01s, unless someone decided to pop out the laminar screen in the stock MAF or go to the Granatelli unit.

The workaround is simple in its application, and my question to you is, have you gotten a code? It will occur within the first 50 miles if at all. If not, don't worry about it. This post is to explain everthing we have learned about the 2002 trims.


Jim



Thanks for helping on this thread. I missed it or would have answered it. Nice to have friends on the forum that look out for Halltech.

:)
 

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Discussion Starter #8
Thanks Cap'n, that's my question, his email contradicts that post.

Jim,
Your email had made me feel that the T-1 had to have an injector change to be done right. You said " the stock injectors are way to small for any mod". That's really confusing me, your other posts lead me to believe the stock injectors should be fine.

Which is it????
 

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sdz06 said:
Thanks Cap'n, that's my question, his email contradicts that post.

Jim,
Your email had made me feel that the T-1 had to have an injector change to be done right. You said " the stock injectors are way to small for any mod". That's really confusing me, your other posts lead me to believe the stock injectors should be fine.

Which is it????
Are the stock okay?
 

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Stock injectors are ok. You should not have any problem with the stock injectors and you should get the 16 RWHP.

However, if you want more HP out of this mod, then upgrade injectors to fix the fuel-trim issue.

I will be installing just the T1 initially but I think that if there is still another 15 or more hp on the table available through new injectors or possibly the MAF Translator/Halltech Black Box/etc., then that may be stage II.

- Charley
 

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95% duty cycle!!!!!

I just posted a reply to a similar question about replacing the stock air box. But in it I said:

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I installed several mods that effected the AFR, the Halltech TRIC/Cobra, a TB heater bypass, and I "lost" my cats with just an X-pipe back to the mufflers.

I can't say which mod produced how much of the lean condition, but the total was 18% lean(!), that is, 18% extra fuel was required to get back to stochemetric.

This much extra fuel runs the stock injectors very near their limit (80% duty cycle is supposed to be the max). Because of this, I changed to SVO 30# injectors. (Other people sell similar injectors for 2-3 times the price, but these are race quality and work just as well for about $260.)

It turned out on my car that with the SVO injectors, the LTFTs were almost back to zero (the ideal). This was **just an accident** -- it could have been one way or the other. But I also got an EASE PCM scanner to determine this, and also installed a MAFT to allow me to fine tune the AFR.

Many of our "C5 tuners" apparently thought that they could sell their mods, and that the PCM would "re-learn" to compensate and add fuel to produce the extra HP. But because the GM algorithm in the PCM was not designed to compensate for mods (and there is no practical way I know of to modify the GM code), you leave a lot of power on the table if your LTFTs are not very near zero.
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(the same can be said for running the injectors at more than 80%)

The bottom line is that 95% duty cycle on the injectors is *way over* their rated capacity. You need a PCM scanner to find out what **your car** is really doing, but the consensus seems to be that mods which significantly increase air flow cause a similar condition. (Remember, the 95% duty cycle is only at WOT and red line, at lower RPMs, you will not be anywhere near this.)

Find a friend with an EASE scanner and check how your AFR is doing. If the LTFT is above +12-15%, I'd suggest getting a set of the SVO injectors and re-checking the LTFTs.
 

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So does anyone know the difference in the injector size between the 01 and the 02???
 

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JimGreen - Where did you pick up your SVO injectors - part numbers? TIA!
 

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TAMUz06,

Try:

<http://www.thefordsource.com/store/motorsports/fuel_3.htm>

You want the 30# parts, M9593B302 - $239 + shipping.

Remember, the fact that these injectors almost zeroed out the LTFTs on my car with my mods is no assurance that the same thing will happen on your car. You need to get the injectors, let the car "learn" the new equipment, and find a friend with an OBD-II scanner to check what the new LTFTs are. You may need to also get a MAFT to do fine tuning like I did.

HTH, Jim Green
 
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310cc Injectors

The T-1 does not make the Z06 run lean. The LTFs are simply the result of the descrepancy between expected air and actual air seen at the O2 sensors. The PCM will automatically add fuel trim to each fuel cell to achieve the 14.6:1 a/f ratio built into the PCM tables. Your injectors, however are 255cc/min @43psi for the 2002 Z06 (same size as our 2000 LS1 coupe). With new airflow, they are running at way beyone the recommended industry standard of 80% duty cycle.

Here are the facts:

1) The T-1 adds 8% to more airflow to the Z06 at WOT, If you can keep the a/f ratio at WOT at the factory setting, you will gain that much more HP and Torque in WOT (That is the hard part) If your Long Term Fuel Trims in cells 1-19 are +18, then addition fuel will be added to WOT (which is fuel enrichment code already) bringing the a/f ratio down below the factory setting, or running your Z06 rich in WOT, not lean. The 310cc/min RC injectors remedy this problem. The LTFs return to baseline.

(Why do bigger injectors do this? Let's say the fuel cell 7 is at +18% in bank 1 and 2. That means that the O2 sensors corrected the a/f ratio in that cell by adding pulse width (length of time the injector is open) by 18%. If the new injector adds more fuel than the old injector for the same given pulse width, the O2 sensors automatically pull the pulse width down due to a rich condition "seen" at the sensor. The a/f ratior stays at 14.6:1, but the pulse width returns to baseline if the injectors are balanced. So now your fuel cell reads zero to slightly minus, which is perfect for best power at WOT)

2) The 2002 screenless MAF contributes to the amount of added fuel correction needed at the O2 sensor, since without the laminar airflow screen, it "misses" some of the actual airflow at the MAF, which it found at the O2 sensors and create this delta that shows up in the LT Fuel Trim table. This is why the codes. The 2001 Z06s never coded with our intakes, since the injectors were larger, and the screened MAF did a better job of registering the true airflow.

3) The injector size for the 2002 is 255cc/min @43psi or approximately 24.3 lb/hr. and are too small even for the stock airbox. http://www.CorvetteC5.com click Fuel Injector Sizing.

4) The stock 2002 injectors will work with the T-1, but are at 100% duty cycle at high rpm, and should be sized so that they are at 80% duty cycle. Kinda like running at 105 mph in third, vs 105 in fifth. At normal rpm, they are fine.

5) The 310 cc/min RC Injectors are balanced and blueprinted racing injectors and contributed to our gaining over 30 RWHP over stock. The T-1 alone will net 16 RWHP or around 365 RWHP total. They also feature all stainless inerts. The 30 RWHP number also included our ported throttle body, and the AFR Calibrator.

6) The injectors are definitely a must with an 8% gain in flow for maximum HP and torque and bring the Long Term Fuel Trims back to zero or slightly minus. This allows WOT to be dialed in accurately for max HP.

Halltech now has the Accel Fuel Injectors and MAF Translator available for a lower cost option for those that want to try this combo rather than the combination we dynoed at 381.2 RWHP.

Jim Hall
 

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Jim

the 2001 LS6's have bigger injectors than the 02's, correct? So we don't have to worry about that when we put the T-1 on?

Mike
 
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Re: Jim

MSiska said:
the 2001 LS6's have bigger injectors than the 02's, correct? So we don't have to worry about that when we put the T-1 on?

Mike
They are larger. The T-1 will have no problems at all on the 01s.

In fact, the screen can be removed from the MAF if you like.

Jim
 

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Jim, another thought. :eek: I was talking with Ranger yesterday and mentioned I was buying the T-1c. As you know, he has the TRIC w/Cobra. He hasn't taken out his screen and hasn't had any probs. So, with the T-1C, you don't have to take it out either, I take it? By the way, John said he was having a little surging between 1200-2500 rpm at light throttle openings with the new Z1000 filter. He didn't have the problem with the donaldson. Any reflections you might be able to give?
 

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From what I have read, and heard, (do not have enough miles on my setup to comment on the rich / lean code setting issue) it looks like the T1 on a fairly stock 02 Z06 works great as far as performance goes. It will work even better with a MAFT or the other $495 gizmo Jim sells when the AFR's are adjusted.
The injectors come into play because the stock ones are working so hard that their tongues are hanging out at close to their maximum duty cycle. So the larger injector does not have to work as hard as the stock injectors, and is able to provide even more fuel when of if neccessary.
I guess we need to hear from folks that have this set up (and no injector upgrade) and a fairly good amount of miles on their cars to know if it poses a problem down the road.
I would also like to know if the only thing that is a problem with working an injector at or near its maximum duty cycle is the failure of that injector, or, is what happens when an injector suddenly fails, if that is what the real problem is.

Just some more of my miscellaneous ramblings:eek:
 

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My understanding of injector duty cycle has more to do with maximun fuel flow rate than wear. Actually, an injector dithers (oscillates up and down sllightly around the mean open position commanded) to provide the proper opening (orfice) for the commanded fuel flow. A wider (longer) pulse would cause the injector to dither less - not more. The problem is that when an injector gets up to about 80% duty cycle it reaches maximum flow potential. Longer pulse widths do mean more current and therefore more heat. But injectors are designed for that and operation at or near maximum flow would only occur at WOT with high rpm. So it's OK if the duty cycle is near 80% as long as the fuel flow can support the HP being produced. Remember, that max flow needs to include cold day temps at high baro pressures.
 
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