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Discussion Starter · #1 · (Edited)
Hi,

Over the weekend I removed the screen from the MAF on my 2001 Z06. I also drilled a hole in the throttle plate as per Halltech's instructions and completed the idle relearn process.

I certainly don't have any problems with surging at idle, BUT i do have significant surging when in motion. Example: I was crusing along the freeway yesterday at 65-70mph, around 1500-2000 rpm in 6th, and the car was surging quite badly. Under acceleration the car performed well, the problem seems to be when you back throttle.

If I pressed the gas pedal to bring my speed up a little, and then let off, the car would buck and surge and felt generally very rough.

I called Jim this morning and he told me that this is to be expected with a 2001 with no screen and that the problem is caused by a lean fuel condition. My car is NOT throwing any codes though. I am going to try the NEW Halltech Z1000 filter to see if this improves things any.

Is anyone running a Halltech TRIC with a 2001 and no MAF screen that has fixed the surging?

Anyone else have any suggestions???

If I can't fix it then the screen will have to go back in because I can't live with the car the way it drives now! :( :-?

TIA! :cheers:
 

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Replace screen, see what happens....or, put a rivet in back in the TB hole...why did you drill it out, that usually is left to cammed cars who have idle issues... :-?
 

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Discussion Starter · #4 ·
Thanks guys.

TAMUz06- I drilled the hole because that was Halltech's fix for the the surging problem on the Z06. Like I said before, I don't have any surging at idle, but I guess it doesn't solve the problem when driving. :(

I do have another MAF with screen, but I was interested to see if anyone else has successfully overcome this problem. I've heard of many other people removing the screen on 01s without incident. I just wondered if anyone has it working well with the TRIC.

Is there a MAFT available for the Z06? Might this cure my problem?
 
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EvilZ06 said:
Thanks guys.

TAMUz06- I drilled the hole because that was Halltech's fix for the the surging problem on the Z06. Like I said before, I don't have any surging at idle, but I guess it doesn't solve the problem when driving. :(

I do have another MAF with screen, but I was interested to see if anyone else has successfully overcome this problem. I've heard of many other people removing the screen on 01s without incident. I just wondered if anyone has it working well with the TRIC.

Is there a MAFT available for the Z06? Might this cure my problem?
We have never had a surging problem on the 2001 Z06, primarily because we recommended leaving the screen in place.

Since GM took the screen out in 2002, I would assume that they recalibrated the PCM for this modification. We recommend the hole to smooth out the minor surging found in the 2002 with the TRIC only. The SideWinder has no problem at all since it is not a ram air system.

2001- TRIC Leave the screen alone.

2002- TRIC- Drill the hole in the throttle plate if you notice minor surging during coasting speeds. This eliminates it completely. This subject only came up since the screen is gone from the factory.

2001-02 T-1 SideWinder: No issue at all. Runs better than stock, with incredible throttle response. With 432 HP and 420 ft. lbs. torque, no more needs to be said.
 
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MAF Screen

The stock 2001 MAF flows 880 cfm. The Z06 needs 600 cfm to support 346 cid at 6700 rpm at 85% volumetric efficiency.

By removing the screen, the volumetric effeciency might improve somewhat, the the screened MAF flows much more than necessary to support the hp requirements.

The 75.5mm intake manifold is much more restrictive than the 88 mm MAF.

Drill size .155" -one hole as shown.

Same as on the F-body LS1 TBs.

Jim
 

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Discussion Starter · #9 ·
RG- I drilled the same size hole as Jim specified on his website, 0.155" (5/32")

Jim- Thanks for the clarification. I wish that I had spoken to you before I made the mod. My understanding from your posting last week was that the throttle body hole would fix surging on the 2001 and 2002. If I now replace the screen is the hole in the TB going to cause me any problems? Do I need to replace the throttle plate now as well???
Can I run the sidewinder with no screen on an 01 and eliminate surge? Would this combo make more power than a TRIC with the screen?

TIA.
 

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You shouldn't need a whole new plate...but lots of people have drilled too big, and simply placed a small rivet back in the hole to seal it up, then drill the proper hole...
 
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Hole isOk

I still have the hole in the throttle plate with the T-1 intake, and everything runs fine.

The hole is an standard hole on the LS1 F-body TBs.

Jim
 

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Re: Hole isOk

Halltech said:
The hole is an standard hole on the LS1 F-body TBs.

Jim
Ok...that's why I was a little confused...:) I didn't know the LS6 TB plate had no hole...I was thinking that you drilled the stock hole BIGGER...:)

Thanks for clearin that up, Jim!


<--- feels smarter

:guiness:
 

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EvilZ06 said:
Thanks guys.



I do have another MAF with screen, but I was interested to see if anyone else has successfully overcome this problem. I've heard of many other people removing the screen on 01s without incident. I just wondered if anyone has it working well with the TRIC.

I removed mine a couple of weeks ago without any problems and I just completed a 1200 mile trip to Atlanta.
I did notice a slight surging when backing off the gas when I was in the triple digets though, if you want to call that a problem.
 
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That should cure it.

We developed the Magic Box to offset this condition last year. It richens the mixture just enough to offset the lean condition caused by the screen removal and ram air effect at the MAF.

Call me tomorrow, and I'll ship you one to try out. It works with the Granatelli MAF as well.

The MAF Translator should work as well but ours is free.

Jim
 
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EvilZ06,
I have analyzed the test runs that we did at my garage this weekend and promised I would give you some results to use to help show the problem and to help resolve it.

Two test runs were done with outside temperature of 80 degrees.
Each run consisted of 12 miles of 15 miles of distance, using all RPM, gears, and throttle ranges. This included stop/go city and highway driving while I monitored and collected PCM functions status while you drove the car in the manner you do.

Both test runs used the exact same roads and distance to limit any changes and 2nd run was done within 10 minutes of completing first test run.

The following is what I determined via PCM data collected via a Ease enhanced powertain scanner connected to the PCM.

]Mark's Z06 Test Results

NOTE: the trace consisted of over 3,600 PCM read cycles, but to make this viewable using less screen space, the above was sorted to show knock and lean AFR issues. Also content important has yellow background.

Your surging issue is due to your long term fuel trim being 22 percent too lean. The removal of the MAF screen itself did not drive the leanness to that high of a level, but the other mods combined took your Z06 from being a performer, to high heat generating engine.
Even with the MAF screen installed, the existing mods drove the AFR out of a performance window.

You can see within this results sheet :

LTFT far to lean
Lean condition drove engine knock high, for both WOT and normal driving conditions). Cell 22 is WOT when TPS ( throttle) is greater then 99.5% on. Cells 1-19 are when you are pushing on the gas pedal, but not to the floor.
As seen knock is ocurrung in all cells and TPS position.
causing lessor performance at WOT due to timing on;y being an averge of 25 degrees ( about 3 degree loss, that also lowers maximum torque).
As seen by the injector pulse width, the PCM was attempting to go richer but could not achieve better then the 22 % lean average.
Intake Air Temp (IAT) was 5 degrees hotter then outside temps, thus air intake needs to be improved for IAT should equal outside temps when moving fster then 20 MPH.
The engine water temps spiking 220 degrees further hinders a lean condition, and the lean AFR itself helps drive the engine temps up due to hotter internal temps due to too lean buring AFR forcing pistions, sparkplugs, etc to run much hotter.
You'll notice engine knock was present no matter if the RPMs or speed were low or high.

The surging issue was clearly due to the leanness and to test this and to also reduce the knock issue. I hardwired in a MAF translator and simply set the AFR to reduce from a 22% lean down 5% to 16%.

Apon doing that and then repeating test run, knock went from being triggered 43 times to only 14 and all surging was gone ( but not totally when A/C is on).
By further adjusting AFR with the MAFT, both ill conditions can overcome the mods causing the conditions but I do not agree in total to this type pf fix.

The reason is to fight off a lean condition this far off of being perfect ( a LTFT of zero) you have to drive the PCM to go richer which them means it also drives WOT timing down that will also reduce performance.

You can either resolve the mods causing this over lean condition by vendor correcting or removing such mods.

Use the MAFT to drive LTFT as close to zero, but lean enough to maintain about 28 degrees of WOT timing, but not at the expense of increasing knock, which wold retard that timing

Or as I and others have done go with a larger injector such as SVO 30s, and tune out richness, that means going leaner, drives WOT timing up.

I suggest for next testcase, you adjust base of MAFT another 5% richer and re-scan PCM to determine if that is a short term correction.
Feel free to contact me for more idepth information of test results.


EvilZ06 said:
Hi,

Over the weekend I removed the screen from the MAF on my 2001 Z06. I also drilled a hole in the throttle plate as per Halltech's instructions and completed the idle relearn process.

I certainly don't have any problems with surging at idle, BUT i do have significant surging when in motion. Example: I was crusing along the freeway yesterday at 65-70mph, around 1500-2000 rpm in 6th, and the car was surging quite badly. Under acceleration the car performed well, the problem seems to be when you back throttle.

If I pressed the gas pedal to bring my speed up a little, and then let off, the car would buck and surge and felt generally very rough.

I called Jim this morning and he told me that this is to be expected with a 2001 with no screen and that the problem is caused by a lean fuel condition. My car is NOT throwing any codes though. I am going to try the NEW Halltech Z1000 filter to see if this improves things any.

Is anyone running a Halltech TRIC with a 2001 and no MAF screen that has fixed the surging?

Anyone else have any suggestions???

If I can't fix it then the screen will have to go back in because I can't live with the car the way it drives now! :( :-?

TIA! :cheers:
[
 

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I agree with Jim. I had taken the screen out and then down the line I removed my magic box. Surging was not so much a problem but with the gas we are getting, there was a lot of pinging. So I replaced the black box and it definitely has helped with the pinging and surging. I don't know if this makes sense in terms of the pinging----but it worked.:guiness:
 

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Discussion Starter · #19 ·
John- (TeamZr1) Thanks for posting the results of our test runs from Friday. I was going to post the details myself but I don't think my explanation would have been anywhere near as good as yours is! ;)

Thanks again for helping me install the MAFT and analyzing the data. I hope other members of the forum will read these posts and benefit from the information here.

KellyZ06- Jim did suggest that I try the magic box, but I decided that in my case I would be better off paying a little more and getting the MAFT. The MAFT is adjustable so it can be used with any future mods that you add to the car. The Magic box is set up to complement the Halltech intake and (as far as I know, Jim tell me if I'm wrong) is not adjustable.

As John said in his post above, my car was almost certainly running on the lean side before I removed the MAF screen. The screen just put it over the edge and gave me the KR and surging.

This just goes to show that using ATAP, EASE or another scanning tool is a good idea when you modify your car. Each engine is slightly different, and each combination of mods produces unique results. In my case the TRIC/MAG, ported TB and screen removed from the MAF gave me a very lean condition.

I'll post again as I make adjustments to the car's tuning and let everyone know how it goes.

:cheers:
 

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Discussion Starter · #20 ·
latest update - added 30# injectors

After talking to John I decided to upgrade from stock to the SVO 30# injectors. This meant that instead of setting the MAFT to 10% rich, we were able to go 10% lean.

Once the injectors were installed we performed an idle relearn (with AC on and off) and then took another test drive with the Ease powertrain scanner.

The results- absolutely ZERO KR at any speed or rpm and we also gained around 2 degrees of timing at WOT! :D The car feels very strong and pulls hard.

I will be dynoing the car on December 1st at the next bay area dyno day. It will be interesting to see if the SOTP holds up!

Hopefully John will provide a more detailed explanation, and possibly put up the scans.

Thanks! :cheers:
 
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