Throttle Body and MAF Question
Thread Starter
Safety Car
Joined: Aug 2011
Posts: 4,447
Likes: 409
From: Portland OR
Throttle Body and MAF Question (Fixed)
Was there any difference in the TB opening size from 2000 to later versions?
Mine is 4" OD, but I don't know if it is original to my 2000 C5.
Also, was the later MAF (5 pin) the same size as the earlier 3 pin?
Mine has a late model 5 pin, no screen.
I'm trying to diagnose poor 1/4 mile performance along with P0101 code while drag racing. The car is 10mph off from where it should be.
Thanks,
Ron
Mine is 4" OD, but I don't know if it is original to my 2000 C5.
Also, was the later MAF (5 pin) the same size as the earlier 3 pin?
Mine has a late model 5 pin, no screen.
I'm trying to diagnose poor 1/4 mile performance along with P0101 code while drag racing. The car is 10mph off from where it should be.
Thanks,
Ron
Last edited by RonSSNova; Sep 24, 2011 at 09:29 PM. Reason: Update
Burning Brakes
Joined: Oct 2004
Posts: 931
Likes: 35
From: Rowlett, Texas
No difference in all the C5 throttle bodies.
The '01-'04 used a slightly larger MAF with an integral temp sensor, thus the difference in the wiring.
The later MAF will work on the 2000, but only if it is programmed correctly. If you just pop one on with a wiring harness adapter, it will not function well at all. An additional issue is screen removal. Depending on your air cleaner setup, this can have minor or major negative effects. The code 0101 is a MAF malfunction, so you definitely have something going on.
Choices are to get the current MAF checked and tuned by a pro, or revert back to a 2000 stock MAF. If your car is less than 400HP, then the stock MAF with the screen intact will rob Zero HP.
The early C5's gained a few ponies by removing the screen, but it was not due to airflow increases, but rather to a leaner fuel ratio created by screen removal, as the '97-'99 were set pretty rich.
DG
The '01-'04 used a slightly larger MAF with an integral temp sensor, thus the difference in the wiring.
The later MAF will work on the 2000, but only if it is programmed correctly. If you just pop one on with a wiring harness adapter, it will not function well at all. An additional issue is screen removal. Depending on your air cleaner setup, this can have minor or major negative effects. The code 0101 is a MAF malfunction, so you definitely have something going on.
Choices are to get the current MAF checked and tuned by a pro, or revert back to a 2000 stock MAF. If your car is less than 400HP, then the stock MAF with the screen intact will rob Zero HP.
The early C5's gained a few ponies by removing the screen, but it was not due to airflow increases, but rather to a leaner fuel ratio created by screen removal, as the '97-'99 were set pretty rich.
DG
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
You'll get many opinions on larger T-Bodys--My experience is that there is no advantage to going to a larger TB on a stock cubed engine or an engine that is not run consistantly above 6200 RPM's
Same for the MAF--My car with 400 RWHP--I still run the stock MAF--I did remove the screen but as a tuner i have the ability to correct the MAF table--If you don't have the sofware leave it be----It takes hours and hours of data-logging and recording to correct the leaness caused by removing the screen or changing to a larger MAF-
$$ and effort best spent elsewhere !!
My opinion is that if you wnna run what you have--you just need a complte tune with HP or EFILIVE----to correct for the MAF errors and most likely off fuel trims---
REASON for poor top end charge is that IF your MAF table is off due to leanness from your T-Body-CIA or MAF or screen removal- then at PT or launch--your ECM is adding fuel via your fuel trims to correct the fuel back to 14.68 (Stoich)--HOWEVER if your ECM even breifly at launch is adding fuel--that % is ADDED to your WOT fuel as well as a safety
Example --if it's adding 10% fuel at launch or P/T--then it adds that same 10% at WOT !! making your WOT fuel pig rich-----
making it lazy and killing top end HP---
Same for the MAF--My car with 400 RWHP--I still run the stock MAF--I did remove the screen but as a tuner i have the ability to correct the MAF table--If you don't have the sofware leave it be----It takes hours and hours of data-logging and recording to correct the leaness caused by removing the screen or changing to a larger MAF-
$$ and effort best spent elsewhere !!
My opinion is that if you wnna run what you have--you just need a complte tune with HP or EFILIVE----to correct for the MAF errors and most likely off fuel trims---
REASON for poor top end charge is that IF your MAF table is off due to leanness from your T-Body-CIA or MAF or screen removal- then at PT or launch--your ECM is adding fuel via your fuel trims to correct the fuel back to 14.68 (Stoich)--HOWEVER if your ECM even breifly at launch is adding fuel--that % is ADDED to your WOT fuel as well as a safety
Example --if it's adding 10% fuel at launch or P/T--then it adds that same 10% at WOT !! making your WOT fuel pig rich-----
making it lazy and killing top end HP---
Thread Starter
Safety Car
Joined: Aug 2011
Posts: 4,447
Likes: 409
From: Portland OR
thanks.
I have studied the 2 different MAF sensors and understand they aren't interchangable without changing the tune.
So the question becomes, does my car have the tune changed for the different MAF? I bought the car as it sits.
We did download the tune to HP tuners. Can we tell from that? Compare to a stock tune that I think we can find somewhere.
Otherwise I'll find a stock MAF and see what happens.
I don't want to pay to have this checked out and possibly retuned because I bought the car to modify over the winter. No sense paying for a 2 week tune. I'm in Portland and the rainy season is right around the corner.
One last question. Assuming the car was not tuned for the 5 wire MAF. Will it run and drive reasonably normal? in other words will the computer be able to relearn for part throttle and just be way off at WOT or will it be wrong all together. Because it does run and drive ok, not great, but ok.
Ron
I have studied the 2 different MAF sensors and understand they aren't interchangable without changing the tune.
So the question becomes, does my car have the tune changed for the different MAF? I bought the car as it sits.
We did download the tune to HP tuners. Can we tell from that? Compare to a stock tune that I think we can find somewhere.
Otherwise I'll find a stock MAF and see what happens.
I don't want to pay to have this checked out and possibly retuned because I bought the car to modify over the winter. No sense paying for a 2 week tune. I'm in Portland and the rainy season is right around the corner.
One last question. Assuming the car was not tuned for the 5 wire MAF. Will it run and drive reasonably normal? in other words will the computer be able to relearn for part throttle and just be way off at WOT or will it be wrong all together. Because it does run and drive ok, not great, but ok.
Ron
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
I know that with EFILIVE you can get the STOCK tunes from a site called http://holdencrazy.com
Don't know if there is a site for HP---however you can download the FREE EFILIVE software demo to open the files and get the stock tune from holden and just compare the #'s visually--
Don't know if there is a site for HP---however you can download the FREE EFILIVE software demo to open the files and get the stock tune from holden and just compare the #'s visually--
Thread Starter
Safety Car
Joined: Aug 2011
Posts: 4,447
Likes: 409
From: Portland OR
Thanks guys.
Tblu92, I think we were posting at the same time. So you read my mind and answered my questions before I asked them. Good job!
This is my first dive into EFI and the LS engine. The performance wasn't surprising, because the car just felt wrong at full or heavy part throttle.
Learning all this stuff is one of the reasons I bought this car. And isn't the C5 a nice package?
Thanks, I know what to do now.
BTW, I totally agree that adding airflow to an engine that doesn't need it is a waste of time and $$$$
Ron
Tblu92, I think we were posting at the same time. So you read my mind and answered my questions before I asked them. Good job!
This is my first dive into EFI and the LS engine. The performance wasn't surprising, because the car just felt wrong at full or heavy part throttle.
Learning all this stuff is one of the reasons I bought this car. And isn't the C5 a nice package?
Thanks, I know what to do now.
BTW, I totally agree that adding airflow to an engine that doesn't need it is a waste of time and $$$$
Ron
Thread Starter
Safety Car
Joined: Aug 2011
Posts: 4,447
Likes: 409
From: Portland OR
I bought HP tuners. I have wanted to learn this EFI tuning for a long time. Part of the reason for buying this car.
Anyway, I discovered that my car has not been re-tuned for the 5 pin MAF. The table is stock.
So as long as the MAF isn't of the recalibrated variety (it's a delphi stock part number) then I have found the issue.
I have a stock MAF on the way. Or, I can retune for the 5 wire part.
Fun stuff.
Ron
Anyway, I discovered that my car has not been re-tuned for the 5 pin MAF. The table is stock.
So as long as the MAF isn't of the recalibrated variety (it's a delphi stock part number) then I have found the issue.
I have a stock MAF on the way. Or, I can retune for the 5 wire part.
Fun stuff.
Ron
Thread Starter
Safety Car
Joined: Aug 2011
Posts: 4,447
Likes: 409
From: Portland OR
So I took the easy way out and went with a stock MAF. The engine is stock, so no need for the larger unit.
Also addad a VR Power Duct because whatever was on there was all hacked to make the 5 pin MAF work.
The power duct did not install as advertised, so I made it work without hacking anything. VR owes me an explanation, and some silicone hose, but their email is defunct......whole nother story.
Anyway, what a difference! The car is now agressive where before it was lazy. It actually feels fast! Gads, I've been driving my Cobalt SS too long......
It got to late to head to the drags, but next weekend hopefully.
Thanks for the advice guys.
Ron
Also addad a VR Power Duct because whatever was on there was all hacked to make the 5 pin MAF work.
The power duct did not install as advertised, so I made it work without hacking anything. VR owes me an explanation, and some silicone hose, but their email is defunct......whole nother story.
Anyway, what a difference! The car is now agressive where before it was lazy. It actually feels fast! Gads, I've been driving my Cobalt SS too long......
It got to late to head to the drags, but next weekend hopefully.
Thanks for the advice guys.
Ron
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