So in my quest to simplify the HO cam swap i tried tonight to run my car w/o the sensor hooked up. I also with HPT took out the codes for the sensor as well.

In short it ran and quite well. Im not sure if i was running rich or not but i can tell you it felt like i had the sensor hooked up. no codes no harsh idle nothing just straight up smooth running.

Another good point is there is a DBL fire low rpm VE table which will allow you to tune for the batch fire this creates when running w/o the sensor. So all in all this is going to help big time in my quest to put ho cams on my built motor.

With a stock engine GM is required to program the pcm so the engine will not exceed federal emissions levels if a single sensor fails. With the cam sensor removed or disconnected the pcm changes from sequential injection to batch fire mode. Batch fire was used for many, many years without trouble. Sequential is usually credited with adding hp, but the main reason the OE's use it is for slightly better emissions at low speed. If you try to run big injectors you'll have a tougher time tuning in batch mode, but we're talking injectors large enough to support 350+ hp here, not the slight upgrades many people use.

You get 2 points for thinking about and trying this.

-->Slow

slowolej wrote:If you try to run big injectors you'll have a tougher time tuning in batch mode, but we're talking injectors large enough to support 350+ hp here, not the slight upgrades many people use.

You get 2 points for thinking about and trying this.

-->Slow

I knew the old quad motors ran in batch and that is why Taetschz24 gave me the idea to give it a try.

As far as the injectors go im probably going to run into that problem as i have 60# injectors for the car. But either way i thought above 3k rpms the engine ran in batch fire.

I always wanted to try this when I had my car, good luck and good work!


15.3 @ 89.97mph - '01 SFGT
'98 Acura 1.6EL Sport 5M Y7/Y8 mini me

Lets just say this excites me as i really didnt want to have to wire the cam sync generator even tho it may be something i might do.

ya, every one on quad forums said it couldent be done.... HA, Tom proves me correct.

Owned.

now we need to get that motor built Tommy....


Chris


'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08

Taetsch Z24 wrote:now we need to get that motor built Tommy....


Chris

Money and time have been way too tight lately

...ill be your parts hook up bro.

Chris


'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08

Taetsch Z24 wrote:...ill be your parts hook up bro.

Chris

PMed

Quote:

ya, every one on quad forums said it couldent be done

I guess I didn't see that one or I would have said otherwise.

Quote:

As far as the injectors go im probably going to run into that problem as i have 60# injectors for the car. But either way i thought above 3k rpms the engine ran in batch fire.

Yeah, 60# is big for batch fire. You might end up using an FMU to help. The problem is at low rpm and very low load when you need very small amounts of fuel. A big injector just has to deliver so much fuel each time it opens. Trying to open it for less time results in inconsistent behavior. Add to that the batch fire strategy... fire 2 injectors 2X per cam revolution vs the sequential fire method of firing each injector 1X per cam revolution, and it's dang tough to deliver anything less than too much fuel.

Think of it like trying to water a houseplant with a fire hose and you'll get an idea of how tough it can be.
-->Slow

slowolej wrote:

Quote:

ya, every one on quad forums said it couldent be done

I guess I didn't see that one or I would have said otherwise.

Quote:

As far as the injectors go im probably going to run into that problem as i have 60# injectors for the car. But either way i thought above 3k rpms the engine ran in batch fire.

Yeah, 60# is big for batch fire. You might end up using an FMU to help. The problem is at low rpm and very low load when you need very small amounts of fuel. A big injector just has to deliver so much fuel each time it opens. Trying to open it for less time results in inconsistent behavior. Add to that the batch fire strategy... fire 2 injectors 2X per cam revolution vs the sequential fire method of firing each injector 1X per cam revolution, and it's dang tough to deliver anything less than too much fuel.

Think of it like trying to water a houseplant with a fire hose and you'll get an idea of how tough it can be.
-->Slow

I was also looking at a fmu.

Also im not sure if you know this about my car but i will be running the 2k+ S/C reflash (as i have the 2k computer swap) so do you think that would help any when it comes time to boost and tune for fuel?

Also correct me if im wrong but with the injector firing into a dead cyl its going to cause my wideband to read rich just for the fact i will have raw fuel even tho i could potentionally be lean in the cyl actually using the fuel.

On a side note using batch fire could help with keeping cyl temps down as the fuel will act as a coolant. (also correct me if im wrong)

.... slow, i thought when we are using the MAP VS RPM to control fule, it wouldent have a problem, also there is a non VE batch fire tabe that can be adjusted.... i dont see why it would be harder to tune.... hell OE dosent eaven use SFI above 2800 (or so, from the books ive read.).... i always thought it would be a easy job.... im i worng?


thanks

Chris


'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08

good job tom now i just have to get my ho cams screw doin straight LO cam swap as i planned

..... i orignaly thought about it because i put the BIG cams in the GTZ, so i would have extra HO cams....... the only hickup is that the lifter size is diffrent, but thats fixed by geting a 95 LO cam tower (no CPS) and having the lifter bore's punched out, and just using a HO exhaust cam tower. of corse you will have to get lifter's and there kinda pricey.

Chris


'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08

what about using MSD's cam sync generator???

Quote:

..... i orignaly thought about it because i put the BIG cams in the GTZ, so i would have extra HO cams....... the only hickup is that the lifter size is diffrent, but thats fixed by geting a 95 LO cam tower (no CPS) and having the lifter bore's punched out, and just using a HO exhaust cam tower. of corse you will have to get lifter's and there kinda pricey.

That is the route I am going. I already have a set of 2.3 lifters, HO cams and towers. All I need now is my extra 2.4 intake cam tower punched out for the 2.3 lifters




Jason
99 Z24
157hp/171tq
wheres my boost??

using the msd cam sync could be done i was just looking for a cheaper alternative that would work too.

With the cam sync you just have to find out what cyl or cylinders that are used for reference to spark.

I've been running around for a day now with my Cam PS unpluged, and with the 60# injectors in my car, it runs BETTER then it did before I unpluged the sensor!!!! LoL. I had a nasty mis-fire I couldnt track down....... replaced everything that could have been related, and it was still there. Pulled the CPS, and its gone. Now I just need the HPT cable back so I can delete this pesky CPS code.

(ps. I didnt just throw parts at it trying to get rid of the mis-fire..... I was upgrading for the most part. New plugs, 60# injectors, 2.2 Coil swap....)




SPD RCR Z - '02 Z24 420whp
SLO GOAT - '04 GTO 305whp
W41 BOI - '78 Buick Opel Isuzu W41 Swap

So i guess Bryan just put everyone's big injector theory on the floor. Anyway, does megasquirt give the option to run without the cps, yet still allow sequential firing?



Blew it up, build numbers coming soon

98redcavz24 (LD9Stunner) wrote:So i guess Bryan just put everyone's big injector theory on the floor. Anyway, does megasquirt give the option to run without the cps, yet still allow sequential firing?

If you talking about the theory about running 60# injectors being hard to tune. I am also running the exact same injectors too. I know i will be running into tuning problems its just a matter of getting there.

That is what I was referring to. Abou the megaquirt part of my question, anyone have any insight on that?



Blew it up, build numbers coming soon

Quote:

So i guess Bryan just put everyone's big injector theory on the floor.

lol. I wouldn't believe the potential for problems is gone because one person had good results for one day of driving. Batch vs sequential is an old debate. The guys on the GN list have been going back and forth with it for years. Sometimes batch seems to work better, for others sequential seems to be the best route. The same story has applied on the LT1 lists. And it shows up from time to time on the LS1 and truck lists. But one thing has been true across all lists. Large injectors are large injectors.

Regarding MS and CPS, all control systems need some method to synchronize the injectors to the camshaft position in order to to deliver true sequential injection. Otherwise there's no way for the controller to know what injector to fire first.

The types of problems that can occur when A/F ratios are wrong are worse at idle and very low speed, and they're even worse with a manual transmission due to the large rpm range they cover and the rapid changes they'll go through. You don't have as much momentum to carry the engine through a bad spot at low rpm and there's even less with a standard trans when the clutch is disengaged. Plus the total mass of air moved is less at lower rpm so if you flood the engine it takes longer to clear it out. Tuning for low speed operation is a bigger challenge. When your car runs well enough for you to give it to someone else to drive, someone that doesn't know anything about cars and wouldn't know how to catch a stall or clear a flood, then you've got a decent tune. Anything less and you've made it worse than what it was from the factory.

The problem with large injectors not working well at small pulsewidths has to do with the injectors, period. They simply can't open for a small enough time to give the right amount of fuel consistently. Some of the newer design injectors are a little better in this regard. The Multec II injectors are very lightweight and tend to have better response than the older injectors. Peak and hold low impedance injectors have been better than saturated types for years.

The point is don't expect large injectors to be simple to tune, and expect batch fire to aggravate certain issues with large injectors.

BTW, Brian, did you try an injector pressure drop test to see if one injector wasn't delivering as much fuel, or have you connected a scope to see if each injector is operating properly electronically? You might be masking another problem.

-->Slow

98redcavz24 (LD9Stunner) wrote:That is what I was referring to. Abou the megaquirt part of my question, anyone have any insight on that?

megasquirt does not do sequential fire yet, everything is batch fire, also when you use GM DIS with MS it does not require a CPS at all either.

slowolej wrote:BTW, Brian, did you try an injector pressure drop test to see if one injector wasn't delivering as much fuel, or have you connected a scope to see if each injector is operating properly electronically? You might be masking another problem.

Im glad i got my injectors flow matched withing .5%

Wrench Monkey wrote:

slowolej wrote:BTW, Brian, did you try an injector pressure drop test to see if one injector wasn't delivering as much fuel, or have you connected a scope to see if each injector is operating properly electronically? You might be masking another problem.

Im glad i got my injectors flow matched withing .5%

thanks to me....... no way I was doing the whole ebay thing again with the troubles I had when i bought my green tops from ebay


Team GREEN