types1967

we have to solve this

scalbert

How were you near the armrest?? Just to be clear, where did you tap into the power feed; location in the car??

scalbert

Not too bad and since it is ground it is easy. Power is the troublesome one to wrench on in tight spaces...

But still not a major concern as I see good voltage at other points in the system.

scalbert

Yes, but this may is beginning to appear to be factory related. It may be a monir problem which is not evident on a stock vehicle but becomes visible when the blower is added. It also may be isolated to early 6-speeders only.

Ogolden1

Scalbert, I've also noticed an occasional, intermittent ping with the SC. Mine occurs around/between 3k - 4k RPM under load - especially going up a hill in hot weather. I think it's due to the shitty low octane 91 gas we have here in So. Cal. If I put in a bottle of octane boost, it doesn't ping!

I'd really like to go to the high(er)boost pulley - what are your feelings/opinions? ... Should I wait until you get the IC project tested and get one; and/or wait for the ECU mod as well?

scalbert

The 91 octane is certainly not helping. I would hold off on the pulley until this fuel aspect is sorted out and more testing is done. The IC may or may not help this matter if fuel is still an issue.

Are you monitoring the fuel pressure at all??

But with both the IC and UniChip the ceiling will be raised quite a bit.

Ogolden1

No, I'm not monitoring the fuel pressure.

Also, put me on the list as a DEFINITE purchaser for your IC setup once you get it fabbed and tested!

ModAddict

Back in the trunk, just above the fuel pump access cover is where I tapped the yellow/black wire. On the TL, there is an access panel when you fold the back seat armrest down. From the trunk side, there is a metal hook that hangs down from that area,... that is where I grounded the test lead. Everything is painted back there, so there aren't alot of grounding points. Do I need to tap one of the other wires that go to the fuel pump for a ground to get a proper reading?

By the way, with temps below 60 this morning, my A/F ratio was 10.9:1 at wot, and high rpm, getting on the freeway.

TopGum

To back up a little bit, I am really confused as to how unplugging the IMRC is helping. Can someone educate me on this? And being in THE anal smog state (California), does disconnecting hurt my chances at passing smog. If so, can I just unplug and plug it in as needed? Thanks !

ModAddict

I think it resricts the air flow during the criticle time, richening things up a bit, and helping to curb the detonation. I don't think it will effect the smog test because it only changes above 4k rpm, or so. Yes you can unplug and plug as you wish.

scalbert

The TL must be different, not sure what wires for you then???

Sounds like you originally tapped into the fuel sending unit though. Are there four wires going to it?? Two should be all black and two not...

scalbert

It appears to alter the airflow characteristics enough at the higher revs to eliminate the knock. Right at the VTEC change over the A/F ratio goes lean for a bit inducing knock. By unplugging the IMRC, the boost stays up a little keeping the A/F ratio rich enough to keep knock at bay.

Since the IMRC opens at 3800 revs and it is not emissions related and would not impact the tail pipe numbers. Even with a loaded test the IMRC would be closed anyway. Plus, since there is no feedback to the ECU as to whether or not the plates open; it does not have a changed fuel map like with the VTEC system. To sum up, it is not at all an impact on emissions. By just unplugging the actuator the inspector would never know the difference nor would it change the numbers.

scalbert

Hey Carl or Eric, why don't one of you take a trip across the state of PA to visit the other?? I would like to see what happens when you swap the entire pump assembly from one car to the other. Any chance you guys might be able to arrange this??

Here is why:

I just went out and wired up a SPDT switch with the output feeding the pump. One side of the switch was tied to the original pump power feed and the other side to the same power feed I have for my amp (since it is a direct run from the battery). I also cut the ground connection and rewired it to a solid, local grounding point.

With the pump being supplied by the stock feed, I measured the voltage and it was 12.9 VDC and the fuel pressure was 41 PSI. At the same time I measured the unused feed from the amp and it was at 14.3 VDC. When I flipped the switch to run off the amp feed the voltage dropped to 13.8 VDC but the pressure went up to 46 PSI. The now unused stock power feed measured at the system voltage of 14.3 VDC.

So I went for a drive with the pump being powered by the amp power feed. The pressure shot up to over 100 PSI as always but this time it only dropped to about 97 PSI. Whereas before it would drop to about 90 PSI, maybe a little lower. So the higher voltage certainly had an affect on the output.

So the problem is isolated to the fuel pump assembly; not necessarily the pump it’s self. I suspect a short in it somewhere which is dropping the voltage as the pump won't draw enough current to lower the voltage level. But to test this I'll have to pull the pump which I'll try to do soon enough.

It is interesting that the stock power feed drops out more, when loaded, than the one I provided. I assume it is because of the various connections it goes through along with the smaller gauge wire is limiting it. But still, there should not be this much of a voltage drop.

I suspect that with the full 14.3 VDC on the pump the output would stay above 100 PSI. I also suspect that both Brad and Carl are having a drop in pressure but it is not seen since it stays above the gauges maximum reading value. Anyway, we are getting closer to finding the culprit and half isolated it to a single unit. Now I just need to do the final analysis. If I have to I'll rewire the darn fuel pump assembly...

Smitty

So I take away from all that "You think the wiring is limiting the voltage to the pump"
??????????????????????????????????????????????

scalbert

Not really, I think something is awry in the fuel pump assembly. That is the source for the voltage drop. If there wasn't something pulling the voltage down then the stock wiring would probably be fine.

ModAddict

Good guess, I tapped the wrong wire, yellow with green, so much yellow, and bad lighting, looked right at the time. I can tap the other one if you want, but it sounds like you have a handle on it,..... for now.

ModAddict

I would like to put a "halfer" on the gauge, Or try to recallibrate it so it reads 20 psi less than it actually is, or anything else, so I could see what's going on up there. Any ideas???

scalbert

Wouldn't work, the pressure transducer will max out at about the specified maximum range. By lowering the read value wouldn't give you anymore upper range.

Now I can put this transducer on the bench and determine what the calibration is. I can then get you another unit with a greater range such as 150 or 200 PSI. You would just need to do the math from there...

scalbert

It would be nice to see what the value is just to be sure there is an unusual drop for Eric and I, if you don't mind.

ModAddict

be right back

ModAddict

13.2 VDC at idle

scalbert

Hrmmm, that is low too but not as bad as I am seeing. But not enough to cause the fuel pressure to increase significantly. I would say the difference would yield maybe 5 PSI at the most.

So once again I need to delve further. I am still going to follow this one up though as there might be something going on with the assembly. I need to pull it and check the filter and hose looking for a potential kink.

But regardless I am going to rewire it and get less than 0.100 VDC drop as this is easy and will be needed.

TopGum

Steve and Brad,

Have you been experiencing the ping Eric has? I ask because as far as I have read, Steve bored out his throttle body to 68mm and does not have the IMRC unplugged. So, aren't you pumping in more air than Eric yet are not experiencing the detonation that is plaguing him? I guess I'm confused where he unplugged his IMRC, thereby providing a slightly richer A:F ratio where Steve is pumping more air in yet not experiencing any detonation.

I am trying to understand this before I get my supercharger installed next month. Coming from a guy who cut his teeth turning screws on carburators, you guys amaze me! Thanks for being on the cutting (do I dare say bleeding?) edge.

types1967

i have no pinging issues what so ever since i pulled the imrc.also there is no decrease in performance at all whether its plugged or not.i had slight ping very slight but even that was not good.its been a month now with imrc pulled and running great.soon as we find the voltage problem i will plug it back in but with the new manifold and ic it doesnt matter about the imrc anymore oh and im at 13.06volts

scalbert

Yes, I have a bored out TB but also a ported and polished upper and lower intake manifold; if that makes a difference.

I have run with and without the IMRC and haven't noticed any knock lately. But the coldest I have run in lately is about 65 F and the knock seems to shop up with cooler air; this may be the difference.

The knock is not always present or repeatable and it is hard to say if or when it will happen for sure. Last spring when I put on the high boost pulley I did experience knock so I tried all sorts of things to try and get rid of it including installing an extra injector (shown below). It wasn't until I had gone back to the base pulley that I found an issue with my FPR; it wasn't ramping as it should so I was running very lean. With that corrected I went back and re-tried the high boost pulley and haven't had any knock.

Right now I have the IMRC actuator connector pulled as an experiment and it also gives a smoother delivery particularly around 4k revs. But before this I did have my fuel pressure turned up a bit and did not experience knock. I then went back and dropped the pressure and hooked back up the extra injector to try and balance the A/F ratio by leaning out down low with the lower fuel pressure but supplement the top end.

So as of right now I have the actuator disconnected (which will be removed anyway with the upcoming IC), base pressure being run and the extra injector enabled for the time being (probably not needed).

In theory I should be moving more air than Eric with the TB and manifold work. But I also have a way to supplement extra fuel if needed.

ModAddict

Today on the highway I decided to watch the fuel pressure during a few wot runs. I usually try to watch the road and sometimes the wideband, but with all the FP issues going on it was the FP gauge, right up to the redline at around 100 mph, whatever gear that is. My fuel pressure did come of the pegged position, but did not go below 100 psi, so yes my pressure is dropping at the top end. This was with the IMRC connected, so I thought, since when the IMRC is disconnected, it shows 1psi more boost on the gauge, maybe the FP will stay pegged. Not the case. The same thing happened, right at the top the FP dropped to 100psi.

I do feel the difference with the IMRC off, and agree with Steve, it feels like a smoother power delivery in the midrange.

scalbert

Thanks Brad, that does make me feel a little better. I know there are going to be some variations from vehicle to vehicle; this is nice that we can now share and document this information.

I'll bet if I dropped the ESM setting I would see less of a drop; this may be another variable. In all I feel there are many variables in this equation which amount to the various values we are seeing. The differences in pressure drop may be a combination of voltage drop differences, ESM settings, the ECU tuning (how it is reacting and controlling the fuel trim and subsequently the pulse width) and finally the pump. But now I am not worried about it; it is a known condition which can somewhat be helped. If we need even more fuel then a second pump can be added fairly cheap.

But IMO, it may be moot when the UniChip is ready. When this is ready I will want to drop the pressure and run only about a 4:1 gain rate; maybe 2:1, but run larger injectors. With the lower pressure, flow will increase and we will most likely be fine with this pump.

Regardless, I am rewiring the pump to get full juice to it; if not for anything but piece of mind.

TopGum

What will the Unichip do that a V-AFC won't?

scalbert

The VAFC is worthless on our car when forced induction is added and the Comptech ESM is used.

Our ECU uses the MAP sensor to determine manifold vacuum/pressure. But if it sees a positive manifold pressure the ECU will go into limp mode by pulling timing and eventually setting a DTC. This is why the ESM is used; it holds the MAP signal at a preset maximum value when there is positive manifold pressure.

The VAFC works by modifying the MAP signal +/- X% to trick the ECU into thinking there is more or less manifold vacuum and subsequently adjusting the fuel supplied. But if the ESM is clamping the signal at a preset level, any changes the VAFC would apply are cancelled out.

The UniChip may read the ECU input signals such as the MAP sensor, but it doesn't alter them. Instead it intercepts the output signals to the injectors and ignition coils. This way it can directly control the amount of fuel which is supplied (or ignition timing). IMO, this is a great feature since it initially relies on the factory tuning and you adjust from there but in a direct fashion.

TopGum

What's the difference between a missing link MAP sensor and the ESM from Comptech?

scalbert

I am not sure what you are refering to in "missing link MAP sensor"??

TopGum

missing link MAP sensor

ModAddict

hmmmm.......

scalbert

This would be the one for us:

http://www.synapseengineering.com/html/ml001.html

So it is just a check valve, albeit a nice one. It really isn't too relevant here as we are still working within the designed range of our MAP sensor. We would have to generate about 22 PSI boost before I would worry about damage to the MAP.

ModAddict

It's not that big of a deal, but it would have saved us from cutting the factory wire harness and wiring it up.

scalbert

True...

TopGum

Is there any reason why at the sc install the shop would need to get to the fuel pump? I ask because I will have to pull my sub box if they do.

ModAddict

Yes, the fuel pump is replaced.