OBDII to OBDI conversion finished!

[PaynNSX]

Converted the 1997 OBDII TBW to OBDI w/ AEM EMS. The Conversion included pedal assembly, engine harness, intake manifold, throttle body, and throttle cable from an earlier 3.0L. The conversion was NOT easy...lots and lots of tracing, re-pinning, and removing of factory wires...definately not for the weak of heart.

The setup includes a BaschBoost supercharger, AEM EMS, 3 boost pulleys (8 and 11 psi from Basch, custom high boost pulley untested), low compression build, Walbro 255 pump, RC 720cc injectors, air/water IC, test pipes, and Thermal exhaust.

Roughly 15 minutes after initial startup we had the cold start and idle nailed. 4 Runs later on the dyno with the 11 psi pulley, air fuel ratios were settling in and the car was running flawlessly. We ended up with 405 hp and 285 ft. lbs at 8000RPM - unfortunately, I believe we are approaching the limits of the fuel pump. Air/Fuel climbs a little lean and hp dropped off on top even with the 720s no matter how much we increased the pulse width. I deffinately think there is 425 whp available at this boost with fuel system improvements and closer to 475 on our high boost pulley that was made last week (should be around 14 - 15 psi). Out of the box with 8 psi and the Basch/Split Second fuel and timing controller, the car made 351 whp.

Last point - our in-house dyno is a brand new in-ground MD AWD (inertia / Eddy current loading). After seeing some of the other Dynojet graphs out there for similar setups, our numbers appear low in comparison. We will be running some back to back comparisons on a local Dynojet 248 as well to show the differences.

Will post new results as soon as possible.

Thanks,

Devin Pearce
Payn Technologies
[email protected]

 

[Yellow Rose]

I don't know about Michigan, but in Texas that conversion would not be legal. In Texas, cars 96 and newer are emissions tested by plugging a computer into the OBD-II diagnostics port and linking the information to the Department of Motor Vehicles to pass the annual state inspection.

Folks, there is not a technical reason why a car can't be OBD back-dated. However, if someone is buying a "specialty built" car from out of state, be sure to check what your state's emission laws say.

BTW, mine is a 95......how long did the conversion take - two hours, two days, two weeks, two months?

 

[tunapie]

Sounds like a lot of work. Your injectors are huge and should work. Did you bypass the factory resistor box. Also, how did you build up your aftercooler. A picture would be great. Dan

 

[PaynNSX]

I deffinately wasn't considering emision compliance when I changed away from OBDII. The car was making fantastic power before hand, but I felt more tunability was in order to increase power numbers and reliability after 8 - 10 psi. Fortunately we (MI) do not have emisions.

......how long did the conversion take - two hours, two days, two weeks, two months?

The car has been down for more than a month for other non-related changes, but as far as the conversion goes I would have to guess around 45 - 50 hours. It should deffinately take less time for someone that has done the conversion previously.

BTW - Has anyone else done this conversion yet?

 

[Yellow Rose]

.....but as far as the conversion goes I would have to guess around 45 - 50 hours

Assuming it is done at dealership rates this would rival the cost of a Motec. But you still have to go get a different controller, thus even more $. I have heard that Motec also makes a module that supplements their main EMS, which takes care of the throttle-by-wire obstacle.

Has anyone else done this conversion yet?

Maybe in the near future? Conversion vs Motec. I think Gerry Johnson will be undertaking a similar project.

 

[NoClgDeg]

low compression build

Did you original setup of the BBSC blow up your motor?

 

[sjs]

Very interesting. Thanks for sharing! I have a 3.2 that I may someday find time to put in an earlier car. It sounds like you may be able to tell me a few things since I'll be swapping some of the same hardware but not need to mess with as much wiring.

As for the Walbro, I doubt it is the problem unless it's faulty. Did you get the HP version? Even if not, it can easily handle that demand level. Hook up a pressure gauge and watch it under load. For temporary purposes you can use the tap on top of the fuel filter. It is a small but common size that typically comes in a good shop gauge kit. I’ve had no problems with a simple rubber o-ring seal as came with my gauge even at 90+psi.

As already noted, make sure you jumper around the pump resistor for constant voltage. With a stock ECU that switches to full voltage when needed anyway, but not with the AEM so it may stay in the circuit or go spastic as mine did. Another possible problem is your FPR. Did you retain the stock one? Even if it can handle the pressure side, the orifice back to the tank is too small and can cause pressure fluctuations. (not your lean problem, but worth replacing). AEM has a nice one for a street price of ~$145. Next I would suspect the fuel line and rails. Pressure is great, but you need volume and blowing through a straw is difficult.

Another thing to check is the little relay inside on the firewall immediately behind your head. That goes to the pump resistor (which should be bypassed) but may also be part of the over-pressure circuit. Check the wiring diagram because it may be that the over-pressure switch trips and causes problems. I've yet to track that down but it's on my do-list. Keep in mind that some (many?) of these little things are not controlled by the AEM as they were by the stock ECU, and may be part of the ongoing problem that AEM is having with tuning it.

 

[PaynNSX]

Did you original setup of the BBSC blow up your motor?

No, I spun a bearing on the original motor (on nitrous). The BBSC kit is a great bolt-on kit using the included piggy-back fuel controller. Wanting to run higher boost levels warranted a full build from Basch...Mark B did a great job with the kit and motor.

 

[PaynNSX]

sjs,

I have allready purchased an AEM regulator in prep for the next round of dynoing - very good point you made about the orifice restriction causing fluctuations.

We bypassed the pump resister out of the system prior to start-up like you mentioned. I'll be monitoring fuel pressure through the AEM dataloging next session and will post back what we find.

 

[sjs]

... I'll be monitoring fuel pressure through the AEM dataloging next session and will post back what we find.

I looked for an FP reading but didn't see one. Did I miss it or are you using a generic input? Is there a stock sensor they have mapped or did you add your own?

 

[PaynNSX]

I looked for an FP reading but didn't see one. Did I miss it or are you using a generic input? Is there a stock sensor they have mapped or did you add your own?

Will be using a generic input - AEM sells pressure and temp sensors that work perfectly. In the past, using the AEM EMS, we have monitored pre and post I/C temps, turbo back pressure, etc. with their supplied sensors and available inputs described in their wiring pinout diagrams.

 

[tunapie]

Just to clarify, I was refering to the OE injector resistors on the right side of the engine compartment. Dan

 

[Black&Tan97Tnewportbeach]

Wow! Congratulations! I noticed you mentioned "intake manifold" as a part that was swapped out. Is it actually a different part? The plan I have with Gerry for mine is to get the pedal assembly (done), the 3.0 throttle body (done), and the cable (needed). We will be using the TEC3 which has its own sensors so we won't need to change the harness. We were hoping the 3.0 throttle body would bolt right on to the 3.2's intake manifold as the intake shows up as a single part number for all years. Thanks for the info and congratulations again!

Chris Wolf

 

[sjs]

Just to clarify, I was refering to the OE injector resistors on the right side of the engine compartment. Dan

Ah, got it. I didn't think the RCs would even work with the resistors but I've never tried.

 

[PaynNSX]

We are currently using the NSX 7-wire resistor box to drive the RC low impedance injectors. As far as the manifolds go, I sourced the intake manifold with TB complete from Mark so I never checked the compatability between the 3.2 manifold and 3.0 TB.

The fast idle valve and IAC are bolted directly onto the 3.0 manifold vs. neither being located on the 3.2 (don't quote me - it appears that idle control on the 3.2 is related to the DBW system). This might be one snag when trying to retain the original manifold and swapping the throttle body. Let me know if I'm on the wrong track here.

 

[Elite]

Congrat's Devin on the whole build up. Let us know what the high boost pulley makes when you get the feul figured out. BTW I have known Devin for a while now(he used to live in MN), and is a very knowledgable guy. I would recomend him to anyone who needs work on any car they drive. Any plans to drive your car to MN any time soon? If so I want a ride. Mo - Elite.

 

[4AU4LIFE]

Wow, that sounds great. I would also like to see some pics of that.

 

[NSXTech]

Devon, Thanx for the kind words. Several people asked the same or smilar question, and it relates to which and how many parts are needed for the conversion.
Since I am one of the many sponsors of the OSOFast Team NSX, I supplied them with all the parts they needed except the AEM EMS. Most of the pedal and cable stuff came from ERZ, but the manifod and related parts came from my massive inventory of CTSC install leftove (as in 'not re-used') parts. The list actually came from Andy V, though he didn't know it (no- you weren't sleep-typing again), rather, when we finished Andy's low comp motor before we ever even put the BBSC on, we toyed with the idea of going OBDI just so we can use the AEM. Poor AEM- the most misunderstood (besides mine<g>) product on the market. The thing is a wonderbox. Problem is, and reason for ALL the flames I have read, is that it is just too complicated for the average user. If you can find an experienced AEM tuner (preferabally AEM Certified as am I) who has never done an NSX, it should take 3 to 5 hours for his first NSX (closer to 3-N/A, closer to 5- F/I). If the guy is a REALLY good tuner with experience in at least two or three of the other stand alones out there- maybe 4 to 8 hours. If the guy asks, "What's a serial cable??"- Leave.

I'm glad Devon is having the experience's he is so far. I agree with him that on a dyno - jet, things will climb very quickly. A low comp motor I finished lately is running the same set up on a 3.0L at 5k ft altitude (yep- Denver) and he just faxed his latest dyno to me, showing 395 / 285 ft/lb. Not bad with no air to breathe.

And to the smart --- who had to find SOME dirt,the Denver dude (Bruce M,) like Devon, like Andy,and like 4 of the last 5 low comp motors I have built- they were built before they ever saw a BBSC.

I am happy to share ALL the info I have on this conversion for anyone who doesn't care about smog inspections, as always, at no charge. As to doing the work ay my shop, the rest of the year- or at least till end of November, is already booked. Call Jane if you are interested.

Mark Basch

 

[sjs]

Thanks for your input Mark, as always. What concerns me about the AEM (I was one of the first to get it) is that according to people who have spoken with their people recently, there are still know "issues" with the NSX version. Can you tell us more about that from your experience? For example, back when I was tinkering with mine I noticed a pronounced saw tooth shape in the A:F log. I could tune it essentially flat or at the desired slope, but zooming in revealed a very obvious "wave", approximately 1/2 second peak to peak and more than 1/2 point in amplitude, with the wave top somewhat flat and the bottom quite pointed. I also wasn't able to find quite the right balance of adjustments for decel, as it would drop too low and sometimes stall, but was assuming it just needed more work. Now that AEM seems to have acknowledged a few remaining gremlins I'm not sure what can and can’t be tuned out.

Any insight you can offer would be appreciated by all I'm sure.

 

[sonik]

My friend put the aem on the supra after fulling building up his motor including:
rods
pistons
cams
valves
valve springs...............list goes on and on and when running his aem I guess the version he was running had a bug that caused the injectors to stay open and it ended up filling the cylinder with gas and since you cant compress liquid, the gas goes down into the oil pan and diluted the oil causing his crank to walk. After pulling the cams he noticed they had grooves in them that probably cant be cured by a machine shop. Then when he tore apart his block, all of the upper main caps we groved pretty good from the crank walking up against it. Every piston not only had side load damage to them, but also evidence of piston slap on the intake/exhaust sides. One section of the crank is discolored due to running under high heat with no lubrication, even on the counterweights!!!!. Every single bearing on the rods and mains are grooved, scratched, or completely not even fitting in the main cap screwed. The oil pump is covered with shavings, which is obvious. Also when the crank was walking it pushed the timing belt "keepers" on the oil pump gear into his lower timing belt cover so that's gone too.

 

[PaynNSX]

Poor AEM- the most misunderstood (besides mine<g>) product on the market.

That's no joke! Speaking of the BBSC, I never appreciated the craftsmanship of the kit until I removed it piece by piece to convert the car. For those of you that have not seen Mark's kit in person, I hope that when you get a chance to see one installed, look closely at the beautiful machine work, engineering, and fitment.

Thanks again for all your help and support Mark!

Devin

 

[NSXTech]

Any insight you can offer would be appreciated by all I'm sure.

sjs, All- I'll find time in a day or two to try and share what I've been doing with AEM. I've got three cars in the shop for AEM installs, and I'm doing 4 engine builds at one time (all low comp),
BUT, as soon as I have half an hour (the way I type) I'm always happy to share what I know with all.
On the intakes- there are 4- a)91-94 b) 95 and 96 which added air holes under each injector mount for air to regulate idle speed as the fly by wire caused the air idle motor to dissapear. c)97 thru
2000, and lastly, 2001 thru current which has relocated (slightly) air inj ports. I use the 91-94 in all the 3.2 swaps I do because it allows me to keep all the sensors which means all the wire harness which is CRITICAL because the engine room harness plugs into the cars main harness at three points, so NO, you can not just add the 3.2 ECU because it came with the 3.2 motor you bought. (say that three times fast)

MB

 

[PaynNSX]

Would someone mind posting some pics of the install and car for me if I email them to you?

Thanks!

Devin

 

[NSXTech]

Thanks for your input Mark,

Any insight you can offer would be appreciated by all I'm sure.

Steve, Have you converted the file from .94 to the v1.03 yet?? You can take any map made in v.94 and convert to a v1.03 and that gives you two critical adavantages.
1) is that you can use all the set up wizards in the set up column mainly for sensors. Think you got them all riight ?
Wait till you run the set up wizards for ALL the sensors. It gives you all the relevant options and then enter the values damn close. (the "Set up ECU Wizzard" is at this point, vaporware. When you get the error message that says call AEM for Assistance, save your dime and time. They were just practicing the layout, and it aint up yet.
2) The other invaluable upate is the "context sensitive help" which you find under help. Check the box under help, aaand basically when you're holdind the cursor a feild for a few swconds, it opens up a new info box just about that setting.
Its invaluable.

Cheers, Have fun, My best to Gene

Marrj