Help interpreting AFR log

[jwmelvin]

I just installed a Zeitronix ZT-2. Car is '00 with Whipple CTSC low boost with ESM. I haven't had a chance to put in the MAP sensor but did hook up the TPS and tach signals. Since I don't have extra bungs yet, I put the sensor in the front bank post-cat position.

I think I have a problem, based on what I have gathered from reading threads. Although the AFR should read a bit lean because I'm measuring post-cat (OEM cat), I'm pretty sure it should not be as lean as it appears to be.

Here is a screen shot from the logger software:

Lean! Any help you can give me either in getting the ZT-2 set up better or figuring out what to check next would be most appreciated. I'm guessing I need to check my fuel pressure, replace the fuel filter, and have the injectors cleaned. If there is still a problem after that, then perhaps the fuel pump is next?

Thanks,
Jason

 

[DDozier]

Looking at your logs the car is lean and you should stay out of boost, did you install the Boost-a-pump with the ESM? If you did not you only have half of the CTSC fuel system installed. without the boost in fuel pressure you will not be able to supply enough fuel to richen up the car during boost.

The CTSC fuel system is very simple, the ESM tells the ECU you are at wide open throttle but not in boost even though you are. The boost-a-pump kicks the base fuel pressure from about 50PSI to almost 100PSI when the car goes into boost. This 100% increase in fuel pressure is almost equal to doubling your injector size and is what is needed to richen the fuel enough to be safe. The CTSC kit also included a new fuel pressure regulator as the OEM unit will be swamped by the higher fuel pressures and becomes unpredictable. Without all the pieces installed and tested you can not assume the system will be safe. Once you know all the pieces are there, then test again being very careful to watch the AFR as you enter boost. You should see the AFRs make a dramatic move into the 11's as you increase throttle input and boost comes on.

Dave

 

[jwmelvin]

Thank you so much for responding.

...did you install the Boost-a-pump with the ESM?

I did not install the ESM, it was there when I bought the car. But what do I look for to see the boost-a-pump? Am I correct that it is behind the driver's seat? I'm pretty sure it is there and installed:

The CTSC kit also included a new fuel pressure regulator...

Yes, I do have a red FPR that I believe is the CT unit:

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One more thought: when I tried to monitor/log through the OBD2 port, it does not appear that the car goes into open loop when WOT. It did go open loop at some point or another but it didn't correspond with throttle position like I expected. Maybe that's not a reliable parameter to read from OBD2 but I do find it odd that the AFR is right around the closed-loop point in my log above.

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The OBD2 logs seem to show the short-term trims going to zero as the throttle goes to WOT, so although the open-loop/closed-loop signal does not correspond, I'm guessing the ECM is going to open-loop when at WOT. So I definitely have a fuel issue.

 

[RYU]

Wow! Way too lean. Don't boost.

Knowing the fuel press would be nice. I'd increase the flow on the rrfpr a half turn. Even very small turn increments make a big difference.

 

[jwmelvin]

Thanks; do you know which way I turn the screw to increase the pressure?

 

[RYU]

Unfortunately I forget

I found the answer online. It's a vortech unit iirc

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If you're anything like me... As you tinker more you might be on the verge of a piggyback/ems.

 

[DDozier]

Thanks; do you know which way I turn the screw to increase the pressure?

Wait. we need to verify that the Boost-a-pump is working correctly, you need a multimeter so you can measure DC voltage going to the fuel pump. You need to know how the CTSC is triggering boost, some used a HOBs switch with two wires connected that when the manifold pressure would reach 2-3PSI would short the two wires and trigger the boost-a-pump to raise pump voltage from battery (13.8vdc) to 16 - 17vdc. You could have a bad HOBs switch, bad trigger wire, bad boost-a-pump, or a number of other issues.

First things first, depending on your DIY skill levels you may want to get this into a performance shop that understands how Boost-a-pumps work and are triggered. The Mustang guys have been using them for years so if you are feeling like this is beyond you you may want to start looking there.

If you feel like you can handle this then step one is to verify fuel pressure at idle and with the trigger for the BAP (boost-a-pump) shorted, I would also want to know pump voltage in both states as well to rule out the BAP, if that is all good then you need to rule out the trigger for the BAP they have been know to go bad or get a large amount of oil pooling in the bottom of the intake and causing them to fail. If it is a bad HOBs switch I would add another and abandon the old unit as it requires the removal of the entire intake. Lets cross that bridge later, right now, we need to know the health of the fuel system.

Since you have a ZT-2 adding the fuel pressure sensor would be a good idea but any test gauge with the right fitting can be attached at the fuel test port on the OEM fuel filter.

Dave

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Wow! Way too lean. Don't boost.

Knowing the fuel press would be nice. I'd increase the flow on the rrfpr a half turn. Even very small turn increments make a big difference.

We do not want to do this yet, his AFR is beyond a small adjustment on the FPR, he has a fuel pressure problem that needs to be figured out first.

This is the picture of the remote mounted HOBs switch, is yours like this?

 

[RYU]

I always default to Dave's best judgment BTW. Can't thank him enough for his help thru the years.

 

[jwmelvin]

I will check the BAP input trigger and output voltage. And I will also add a fuel-pressure gauge to the filter. I'm comfortable enough figuring out those things (although knowing more about the specific BAP in there would be nice).

The SC is going to come off in the next couple weeks to replace the bypass hose, so I can change anything else that needs it then. Someone will be doing that work for me. Shad suggested moving the MAP tap to the side of the intake, right under the snout, to avoid the oil-pooling issue.

Will report back some time next week when I know more. Thanks for the help.

 

[DDozier]

The OBD2 logs seem to show the short-term trims going to zero as the throttle goes to WOT, so although the open-loop/closed-loop signal does not correspond, I'm guessing the ECM is going to open-loop when at WOT. So I definitely have a fuel issue.

If the fuel trims go to 0 then you are in power enrichment mode or open loop, OBDII data stream is too slow to monitor that PID, it can take upto a second or two to change the status, this is not what you need to focus on now.

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I will check the BAP input trigger and output voltage. And I will also add a fuel-pressure gauge to the filter. I'm comfortable enough figuring out those things (although knowing more about the specific BAP in there would be nice).

The SC is going to come off in the next couple weeks to replace the bypass hose, so I can change anything else that needs it then. Someone will be doing that work for me. Shad suggested moving the MAP tap to the side of the intake, right under the snout, to avoid the oil-pooling issue.

Will report back some time next week when I know more. Thanks for the help.

If you have the remote mounted HOBs switch like the one in the post above, measure pump voltage with the car idling, then short the two wires across the terminals at the HOBs switch and see if the pump voltage jumps up, if it does the BAP is working, now you need a low pressure source to raise the pressure of the HOBS switch vac line to 3-5psi, you should see the voltage jump again at the fuel pump. If it does then the HOBs switch and the BAP are both working correctly, next step is to verify fuel pressure under both of these conditions.

While you have the vac line to the HOBs switch off blow air through the line to clear any clogs in that line as well, I have seen them fill with oil and then clog and prevent the HOBS switch from triggering correctly.

Dave

 

[RYU]

I will check the BAP input trigger and output voltage. And I will also add a fuel-pressure gauge to the filter. I'm comfortable enough figuring out those things (although knowing more about the specific BAP in there would be nice).

The SC is going to come off in the next couple weeks to replace the bypass hose, so I can change anything else that needs it then. Someone will be doing that work for me. Shad suggested moving the MAP tap to the side of the intake, right under the snout, to avoid the oil-pooling issue.

Will report back some time next week when I know more. Thanks for the help.

A few things i'd consider while removing the blower.
* Contact A.S. Motorsports and look at the phenolic gaskets he provides. Adnan is a great guy.
* Might want to consider DDozier's water spray plate
* Order a Gatorback Goodyear belt
* I found no need going to the TiDave fixed pulley tensioner but a lot like them here

 

[jwmelvin]

Brief update: I looked and the Hobbs switch is screwed to the underside of the manifold, on the forward side near the snout end. So I won't be able to isolate it for a test. I will see what I can do to measure the pump voltage. Should I try to measure while driving so I can see if it is getting the boost signal?

When I have the blower off I will relocate the Hobbs switch. Any advice on where to get one or what one to get? Am I better off going to a piggyback?

 

[jwmelvin]

More update: when I drove and monitored the fuel-pump voltage, it does not change in boost. So I separated the Hobbs switch and jumpered the boost-a-pump leads and the voltage goes to 20.2.

So I know the BAP is working. When I cut the heat shrink off the Hobbs-switch leads, one of the solder joints fell apart. So that could be the problem.

I will continue testing but if the Hobbs switch is the problem, would it be bad to run the fuel pump on continuously boosted voltage for the next week or so? (Shorting out the Hobbs-switch leads.)

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What a day. It turned out to be the solder joint between the Hobbs switch and the Boost-a-Pump. Now that it's reconnected, the pump gets the increased pressure and the AFR is much better. It looks to me like it could still use more fuel though. Could you guys let me know what you think and if it is time to turn up the FPR?
2nd-3rd pull:

3rd-gear pull:

Thanks Dave and Regan for all the help today. It was a really tough day to sit at work and imagine all the problems with my car. I'm glad that I'm learning more about these systems. And I still want to get everything in peak performance before I go changing things around. But it looks like there is no crisis now, right?

-Jason

 

[DDozier]

Great Job, glad you were able to get things going again!

Looking at your recent logs the fuel is about perfect if you are able to run 93 octane and are thinking of adding Meth/Water to your system, if not then I would want to see it a touch richer, once you get your Fuel Pressure Gauge installed make a 2 PSI higher change in your fuel pressure at idle and test again to see if you end up in the 11.7 -11.9 AFR range, keep in mind that the CTSC Fuel System is never going to be a precise table flat fuel AFR plot. You just want the fuel to be as close as possible and trending richer than leaner if possible.

When you service the blower I would move the HOBs switch to a remote location like in the picture I posted above, also if you want to get rid of the hobs switch all together the ZT-2 with a pressure sensor can be used to trigger the BAP with the addition of a simple relay. The ZT-2 can be programmed to monitor boost and trigger an alarm at any boost level so you would have a little more control about when the BAP is turned ON.

Jason, I got your email, the meth plate raises the blower by .75" max, I have not used it with a Targa brace so you will have to measure the space left between the brace and the blower to see if it will work.

Dave

 

[jwmelvin]

Thanks again for your help Dave.

For your meth-spray plate, is the advantage of that over pre-throttle-body spraying that you can spray meth without concern for damaging the SC rotors? And the advantage of meth is better cooling and better predetonation protection as compared to water?

Also, what is cost and lead time of the plate?

 

[DDozier]

For your meth-spray plate, is the advantage of that over pre-throttle-body spraying that you can spray meth without concern for damaging the SC rotors? And the advantage of meth is better cooling and better predetonation protection as compared to water?

Also, what is cost and lead time of the plate?

The major advantage is by not spraying through the blower the meth/water is cooling the charge air only and not having to cool the entire blower and the charge air. I am not sure about what effect spraying before the blower has on the health of the blower but it has been done that way by many people and for many years. By spraying after the blower you are able to use much less of whatever you are spraying to have the desired effect of cooling the charge air.

We have one plate made and in testing, during the process of that install we made a few minor changes to the placement of the spray nozzles, we are calling that the v.2 design and I have the CAD work done but have not cut one yet. Cost will be based on the number of units cut at any one time, the prototype unit cost about $500 to make, if we get a run of 10 units for the CTSC whipple based units together I can get the cost down in the $350-$375 range for the plate, mounting studs, and two nozzles. If you want one plate made I can have it done in a week and it would cost closer to the prototype price.

With Meth I have always run a 50/50 mix of meth and distilled water. It cost you about $9.00 to mix up two gallons, and spraying 300-400cc/min only when in boost should last a long time unless you are using it on the track and even then I would guess that the average guy would use a gallon or two per event. Much cheaper than running race gas to control knock. The water provides most of the cooling effect and the meth raising the knock threshold of whatever fuel you are using. With the CTSC you really need to run both as the OEM timing numbers are only altered by the heat of the charged air from the blower. The OEM ECU sees the raise in IATs and trims the timing back to compensate for the heat, it also adds fuel to richen up the mixture. So if you only add water you could potentially cool the IATs enough to have the OEM ECU add back the timing it took out. The problem with that is the OEM ECU thinks the car has no boost and the timing programmed into the ECU is for a N/A car. So without the ability to remove some timing you can have problems with this setup knocking, to counter that you want the meth in the mix to raise the effective octane of the mixture to avoid knock. As a byproduct the engine will see less IATs, add back in more timing and timing is what makes power. Too much timing makes knock.

It is a balancing act, get it right and the car will run cooler, make more power and be less likely to knock. Winner, Winner, Chicken Dinner!

Dave

 

[jwmelvin]

Thanks for the explanation. Sounds like spray cooling will be better for me when using a piggyback. I think that may be in my future but I'm going to hold off a bit. I may turn up the fuel pressure a couple psi and see where that gets me.

 

[RYU]

Easy fixes are the best! FWIW when I was screwing around with tuning the RRFPR the best I could get was 11.9-12.1. A little itty bitty turn and I remember bit being too sensitive and I was in thq 10.9-11.1. It could have been my clumsy fat fingers. I think you're ok at 12.1 but i'm assuming that's a 1-2nd gear pull. 3rd-4th will give more loading and might produce varying results. 3rd gear starting around 6k rpm was when my POS Walbro 255 started failing.

That's some good power though... until you heatsoak, which it will do somewhat quickly. I'm pretty happy with spraying 100% water in a stock CTSC situation for cooling only.

What a day. It turned out to be the solder joint between the Hobbs switch and the Boost-a-Pump. Now that it's reconnected, the pump gets the increased pressure and the AFR is much better. It looks to me like it could still use more fuel though. Could you guys let me know what you think and if it is time to turn up the FPR?
2nd-3rd pull:

3rd-gear pull:

Thanks Dave and Regan for all the help today. It was a really tough day to sit at work and imagine all the problems with my car. I'm glad that I'm learning more about these systems. And I still want to get everything in peak performance before I go changing things around. But it looks like there is no crisis now, right?

-Jason

 

[jwmelvin]

Okay, my car just spent a week getting the workup by Ben at Daisy Import Auto. He replaced the bypass hose, had the injectors cleaned, replaced the fuel filter, and put in a bung for the wideband that is now pre-cat (I believe in the rear cylinder bank). I also added the Zeitronix MAP sensor. What do you guys think of the following 1st-2nd-3rd pull? Should I still consider turning up the fuel pressure a couple psi? It seems like the AFR is rising as RPM increase.

 

[myhui]

I once read somewhere that the O2 sensor placed too close to the end of the exhaust pipe will read lean all the time due to the exhaust gas mixing with atmospheric gas, thus diluting the exhaust mixture.

Hence sensor position is important.

 

[jwmelvin]

Hence sensor position is important.

Yes I have read that measuring behind the cats can cause a measurement lean by 0.1-0.3. And at the end of the pipe I suppose it could be worse. I'm now measuring before the cat, however, at the end of the header. That is supposed to be the best location.

 

[RYU]

The only thing I don't like about your Afr curve is that it gets leaner instead of getting richer. That could still mean a weakening fuel pressure scenario.

I have my tune ending up around 10.9 at redline simply for added safety. Some may not want to go as rich but that was my tuner and my choice.

I have an old graph with this setup in my photobucket acct but my phone can't attach it here for some reason.

Okay, my car just spent a week getting the workup by Ben at Daisy Import Auto. He replaced the bypass hose, had the injectors cleaned, replaced the fuel filter, and put in a bung for the wideband that is now pre-cat (I believe in the rear cylinder bank). I also added the Zeitronix MAP sensor. What do you guys think of the following 1st-2nd-3rd pull? Should I still consider turning up the fuel pressure a couple psi? It seems like the AFR is rising as RPM increase.

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BTW... You probably have better gas than the crap is Californians get so I'm not as worried in your case. Though 12.6 is a bit too lean for my blood.

 

[ken sampson]

I just had mine tuned by Freed Engineering in Millersville MD. I'm about 11.5 flat across 12.6 is to lean. These guys are very reasonable. My car wanted about 6 more degrees of timing but they would not do it. They also did my E85 Tune. Great people. They had two more NSX's in their shop.
Ken

 

[RYU]

^^^ 6° of advance? Wow... I'm so jealous of your gas. We creeped our way up to 4° but all we saw was detonation. 1° was all my car would be happy with.

 

[jwmelvin]

The only thing I don't like about your Afr curve is that it gets leaner instead of getting richer. That could still mean a weakening fuel pressure scenario.

Yea, that was my thought too. I will try to turn up the pressure a bit and see what happens. Thanks.