Cobra intake installed and running!

98LSC32V

98LSC32V

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So I finally got the C&L intake tube, had to extend the IAT wiring, the problem now is my 9 inch conical is too big and will not fit... it's always something ain't it? Well I fired up the car and it runs, the car doesn't idle that great, the idle wanders from 750 to up to 1000rpm, got a CEL for IMRC'S... uploaded my tune with the IMRC and EGR delete, no more CEL but the idle is still rough... datalogged it and the idle timing was only at 1-2 degrees of timing! With the stock intake and IMRC's it was at 10 degrees on the stock tune and 15-18 degrees on the Sniper NA tune. I added two degrees of global timing and it now reads at 4 degrees, still too low im thinking... also i'm thinking the Cobra tps needs to be calibrated? I drove it down the street real quick and holy crap the throttle response is so much better and snappy... whoever says the swap is not worth it on an NA motor is seriously wrong...

Full swap consists of:
Polished cobra intake manifold
MMR IMRC deletes
Cobra fuel rail with Vortech fuel lines and Kirban adjustable fuel pressure regulator (fuel pressure set to 48psi)
C&L intake tube
 
Glad to hear you got it together. I had the same thoughts on performance after the swap. Let me know how it works at the track. Its very wierd that you had a cel for the imrc delete. I had an idle issue at first then used the mark TB and IAC it was all fixed.
 
Man now you got me all excited! Now you need to take it to the track once you get it tuned right. We need a before and after 1/4 mile time. God this has got me excited!
 
Im running it next Wed... I'm not gonna swap back to the MK8 throttle body for two reasons, the Cobra is twin 62mm vs twin 58mm on the gen 2 plus if you look at the blades when you open the throttle all the way, on the gen 2 they don't open 100% like on the Cobra...
 
98LSC32V said:
Im running it next Wed... I'm not gonna swap back to the MK8 throttle body for two reasons, the Cobra is twin 62mm vs twin 58mm on the gen 2 plus if you look at the blades when you open the throttle all the way, on the gen 2 they don't open 100% like on the Cobra...
Click to expand...

cool
 
Did you change the manifold volume in the tune?
it's way different..
will cause idle issues, WOT fueling issues and transient fueling issues.

I woudn't spray it "hard" until you get the manifold volume set correctly.
 
98 Mark 8 manifold volume 6.78 liters
98 Cobra manifold volume 10.0 liters

THAT is significant and cannot be overlooked.
 
I can't play around with that with special forces but I can probably have someone make me a tune... what exact parameters do you change with regards to intake manifold volume?
 
Ya. Tommy and I know all about that dang intake manifold volume. The Kid helped us out when tuning my car. With Torrie's chip I was pinging, running lean, all sorts of crap. Changed it to 11 (I have an 04 intake) and it all went away.

There is also a setting for the throttle body size, #/m measurement (I think) but I am not sure what its suppose to be for a Cobra TB so I upped it just a little.

Keep in mind any of the above change A LOT of other things. They should be changed first then start adjusting from there.
 
98LSC32V said:
Well I fired up the car and it runs, the car doesn't idle that great, the idle wanders from 750 to up to 1000rpm

datalogged it and the idle timing was only at 1-2 degrees of timing! With the stock intake and IMRC's it was at 10 degrees on the stock tune and 15-18 degrees on the Sniper NA tune.

I drove it down the street real quick and holy crap the throttle response is so much better and snappy... whoever says the swap is not worth it on an NA motor is seriously wrong...
Click to expand...

everything you posted here points towards manifold volume issue.
the snappy response will probably decrease ALOT when you get the MV where it's supposed to be.
I wouldn't WOT this car too much if any until you get a handle on this...
IF the manifold volume was "close" it wouldnt be THAT big of a deal..
but in this case, the difference is almost 50% which is HUGE..and dangerous.

think about it.. you've got more than 40% more air/volume in the manifold than the PCM is aware of.
if it was 4-5% up to 10%..meh.. but FORTY percent.
DANGER WILL ROBINSON!!!
 
I am going to put in my two cents, I do not think the intake volume is causing your problem. when you put your intake on the lower gasket came out of the slot, happens allot when reusing older gasket and even new ones. It got caught in the IMRC plate causing the code the piece breaks off and the code goes away. the vacuum leak will be very small and will cause erratic idle low to high and back. The ECM will compensate with timing and fuel, but your throttle response will seem snappy with a small vacuum leak on one or two cylinders.
 
Serge I am running the mark Tb with mark TPS. I didnt see any size difference between the two TB but I didnt look that close.

Tommy with this MV issue your talkin about I'm not having any issues with the idle at all.
 
Tiltedhalo said:
I am going to put in my two cents, I do not think the intake volume is causing your problem. when you put your intake on the lower gasket came out of the slot, happens allot when reusing older gasket and even new ones. It got caught in the IMRC plate causing the code the piece breaks off and the code goes away. the vacuum leak will be very small and will cause erratic idle low to high and back. The ECM will compensate with timing and fuel, but your throttle response will seem snappy with a small vacuum leak on one or two cylinders.
Click to expand...

I'm not running IMRC's anymore, just the MMR IMRC deletes and all new gaskets. There is no vacuum leak. I put a conical filter on and the idle is fine now in park and in gear. I think it was just due to the turbulance of the air coming into the mass air meter with no filter on it. It still is a bit erratic when you put it in reverse though...
 
98LSC32V said:
Im running it next Wed... I'm not gonna swap back to the MK8 throttle body for two reasons, the Cobra is twin 62mm vs twin 58mm on the gen 2 plus if you look at the blades when you open the throttle all the way, on the gen 2 they don't open 100% like on the Cobra...
Click to expand...

All stock 96-04 Cobra throttle bodies are 58mm.
 
I'm waiting on a custom tune, in the meanwhile i'm compensating for it by putting more fuel into the motor with fuel pressure set to 48psi plus more global fuel as well...
 
I also used the mark TB, TPS, IACV. I didnt have any idle issues, and yes the performance increase was very noticeable on a NA mark. Probably my favorite mod I've done, performance wise and looks.
 
Got an IAC overspeed CEL tonight, guess the IAC that came with the Cobra intake is bad, good thing I have my gen 2 IAC still...
 
Just a little info on intake manifold volume, its my understanding that this is a non-critical setting and that its primary function is to set a base line for the PCM to help set altitude correction via air density, it can have a small effect on throttle response, but should not cause any "terrible outcomes" if not changed.
 
Tiltedhalo said:
Just a little info on intake manifold volume, its my understanding that this is a non-critical setting and that its primary function is to set a base line for the PCM to help set altitude correction via air density, it can have a small effect on throttle response, but should not cause any "terrible outcomes" if not changed.
Click to expand...

Thanks for the info...
 
Hmmm... IAC problem because it is trying to adjust idle and it can't because it has an unknown intake manifold volume... you think you could start putting the pieces of the puzzle together but nope...
 
Again there is nothing I repeat nothing with the intake manifold volume that will effect idle, period. If the idle is fluctuating its a vacuum leak, IAC, timing ect. not manifold volume. I run a cobra intake with a 1/4 inch hat spacer 1" throttle body spacer and split cut back runners and have mine set lower then the stock gen2 intake, and even with the stage two cams I can get the idle rock solid at 700RPM.
PS and have no problem with timing or fuel curves.
 
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