Cartech issues and lowered boost pressure

**fastfour** · July 24th, 2001, 12:45 PM

I've been talking with Holden for a day or so about this and he suggested posting this issue here so here goes: I've had a vacuum leak for some time. The other day G3-teg and I were poking around trying to eliminate it. I've also had a problem of not seeing the 9 lbs of boost I should see with the stepper pulley. I figured since I don't have a cat and a fairly free flowing exhaust (DC 4-2-1 and GReddy PE) that I would see lower manifold pressures.

Anyhoo we tracked the leak down to the cartech. My bleeder valve was all the way open. I would see max fp's of around 82 or so and static will not go lower than 56. Just for the hell of it we screwed the bleeder valve closed and took her for another test drive. HOLY CRAP!!!!!!!! Instead of the 7.5 lbs I was seeing previous to this tweek I'm seeing 9-10 lbs now and what a difference!! The only problem with that is that I'm also seeing fp's of 98 with 310 injectors.

I could care less about the gas mileage. That's not the issue. I just want lower fp's. I have kicked the idea of just removing the stock FPR and just using the cartech but am not totally convinced that will work well enough to check out for now.

My timing is at 14 and the BTC is set on 1 click. Tip in detonation is usually all I see unless I'm in 5th on a fairly steep hill or something. A down shift usually takes care of it. I think the level of timing and little retard I am using (with very little detonation) can only be attributed to the state of tune of the motor and I thank Donny (Import Tuner on this very board) for that. Many of you are using 5-6 clicks on the BTC right?

Sorry for the long post. Just need to have some people on here kick around some ideas on lowering static pressures. Like I said earlier, I can put up with bad gas mileage to have 10lbs of boost. I just don't want to stress the fuel system if I don't have to. Thanks fellas.

Zach

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94 Civic Coupe/LS Hybrid
JRSC@9psi
Turbo Convert
Import Specialty Automotive (253) 473-2606

**JRCivic** · July 24th, 2001, 12:57 PM

I would check two things: First, the Cartech should not affect boost... so chances are good that you have the check valve in backwards. Also, are you using the restrictor ???

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'93 Civic Si H/B with B18C1, JRSC @ 8psi
Best 1320: 12.68 at 110 mph

**zip** · July 24th, 2001, 01:31 PM

fastfour: Does the fp needle sweep across slowly during boost when the bleeder valve is open? If so, then the FMU is leaking. I've had to rebuild the Cartech many times even when using another unit as a back up. The design is good when it works but the sealing system sucks! mad

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Mods

**fastfour** · July 24th, 2001, 01:54 PM

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by JRCivic:
I would check two things: First, the Cartech should not affect boost... so chances are good that you have the check valve in backwards. Also, are you using the restrictor ???

<HR></BLOCKQUOTE>

I'm not using the restrctor and the unit has not been touched other than install since I received it from you. If it's in backwards it was like that when I received it.

Zip, what do you mean by sweep slowly? When I mash it it jumps to around 80 psi and climbs to mid 90's to near 100.

Zach

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94 Civic Coupe/LS Hybrid
JRSC@9psi
Turbo Convert
Import Specialty Automotive (253) 473-2606

**hooper** · July 24th, 2001, 01:57 PM

The Cartech won't affect the boost, per se, but if the boost guage is "tapped" into the same vacuum line as the the one that feeds the Cartech, it could affect the boost "reading". That is, assuming the boost guage is a mechanical unit. If this is the case, the Cartech bleeding off boost may also bleed off the reading the guage receives as well.
I know alot of people have tried several things to drop their idle FP. Larry's mod to the OE regulator, for example. But I TOTALLY removed the stock regulator a couple of years ago with no problems. I tapped a 1/8" pipe thread into the JR aluminum adapter, stuck in a fitting and never looked back. I saw 27psi@idle and let the FMU do the rest. The JR unit worked fairly well for a long time, but I eventually got the Cartech. It widened the range of adjustability greatly.

Hope that helps.

Phil

**5 Liter Eater** · July 24th, 2001, 05:14 PM

Hooper:
Do you not get flat spots in vacuum? Without the stock regulator to raise the FP in the transition between full vacuum and atmospheric I would think it would drive funny out of boost.

Everyone:
I will be installing my JRSC, 310s, Cartech, AEM fuel rail and ENDYN stepper pully next weekend and am debating on how to go about initial tuning. I have the stock fuel pump for now so I should have no problem maintining an idle FP of ~42. Is that too much for the 310s or will the ECU shorten the pulsewidth while in closed loop to compensate. It seems to me that the 310's should work fine in closed loop and should keep me from having to crank up the fuel pressure under boost which may or may not exceed my stock fuel pump's output so it's just a matter of finding the right rise rate on the cartech but it soulds like from what Holden is experiencing this is harder than initially thought.

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Bill Winters
Houston, TX
'94 bone stock GSR w/ home made CAI (Soon to be JRSC'ed)

**JT98CivicEX** · July 24th, 2001, 06:02 PM

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by 5 Liter Eater:
Hooper:
Do you not get flat spots in vacuum? Without the stock regulator to raise the FP in the transition between full vacuum and atmospheric I would think it would drive funny out of boost.

Everyone:
I will be installing my JRSC, 310s, Cartech, AEM fuel rail and ENDYN stepper pully next weekend and am debating on how to go about initial tuning. I have the stock fuel pump for now so I should have no problem maintining an idle FP of ~42. Is that too much for the 310s or will the ECU shorten the pulsewidth while in closed loop to compensate. It seems to me that the 310's should work fine in closed loop and should keep me from having to crank up the fuel pressure under boost which may or may not exceed my stock fuel pump's output so it's just a matter of finding the right rise rate on the cartech but it soulds like from what Holden is experiencing this is harder than initially thought.

<HR></BLOCKQUOTE>

Yes, you will have flat spots from full vacuum to approx. 9 inch of vacuum. The Cartech will pick up from that point on. It will work as long as you never slam on the pedal from full vacuum. You can actually drive it like that by not meshing the pedal too fast, but what's the point? Not only that, the long term fuel trim will try to increase fuel, as the car will most likely running on the lean side while cruising on the freeway @ approx. 20~23 psi and around 10 inch of vacuum without the fpr. Also, 42 psi idle pressure with the 310s will run a little rich. Been there, done that...

JT

**hooper** · July 24th, 2001, 06:41 PM

I didn't notice alot of problems. First of all, the Cartech was set so that it would raise FP at the slightest change in vacuum. Second, the boost came on so quickly with the blower mods that it really didn't have time to do anything but raise the FP. Finally, I was able to fine tune in areas that needed help with the VTEC/fuel controller.
I did have the same problems Holden has talked about. At high(er) boost levels, the Cartech would not bleed enough boost by, and would raise the FP too high. In my case, >100psi FP with 14psi of boost. I never did solve that problem. But it seems that there is a solution. I should have kept at it...