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Thread: My Rom Tuning Endeavors

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Posts: 1-10 of 12
2011-08-16 18:56:51
#1
My Rom Tuning Endeavors
I wanted a space where I could share my experience with rom tuning and the methods and information I have obtained during my road of getting my 240sx SR powered project on the road.

First I am going to shed some light on my project and how it all started.

I originally had a 98 Altima which I had plans on slapping a t25 turbo on, but due to the automatic I changed my mind.

So a buddy of mines had just got his 240sx ka-t out of the shop from being tuned and I had the pleasure of riding passenger seat while it was on 8psi and MY GOODNESS did this car press you up against the seat at only 8psi but it had a nice GT3076 on it so I couldn't imagine what it would feel like on more boost. So from that day I as inspired and wanted a 240sx what would be better then a rwd Altima! Of course it wasn't a Altima which was a 4 door sedan but it shared similar motors.

So fast forward a year and some change and I stumble upon a dirt cheap 240sx with a SR. It had the following:

S13 Redtop SR (stock motor)
Kaaz 2 way lsd
tein basic coilovers
Greddy FMIC kit
Megan Racing manifold
and a few other goodies

Car was missing some odds and ends that was needed to get it running but to make the story short it needed a new motor.

I had my car towed by Brandjayfabrication which is located in MD, they sourced me a new motor set among a few other things.

Work wasn't done by them due to other constraints so I had the car moved to another shop where the motor was installed, wiring for the swap done, suspension work done etc.

While there I paid a guy who comes on this forum from time to time to post to come down and tune my car. I had some issues, and since my car never made it on the road these things didn't come to light until then. Here were the problems:

TPS was bad
Car needed tension rods, front end alignment and a few other things
BOV kept sticking

So he was able to get the car running around 13 afr's at idle and the car didn't see WOT due t the alignment issues it had even at 8 lbs the car would pull hard to the right.

I had the suspension work finished at the shop and once done the car went back to running like crap and ridiculously rich. The idea and the agreement that I had with the tuner was to resolve the alignment issues and come drive up to PA to have the car re tuned on the street. I wasn't able to do that because the car went back running like crap.

So fast forward, a month or so I replace the TPS and set it at .5 volt closed and 5 volts at open. I purchase a base map from JK tuning with the idea to make a trip up to PA to have the tuner finish his work.

With the base map John sent the car still ran pig rich at idle afr's would dip down to the high 9's and low 10's. Also, at idle the car runs really rough, jerks and hesitate as if I have really large cams. I purchase the Nismotronic software along with Tunercode hoping I could create a base map for my setup which is as follows:

Stock bottom end
Cometic HG
BC 264 Cams
BC valve springs
Z32 Maf
JGY fuel top feed rail
75lb Delphi/MSD injectors
Honda Accord Resistor Box
Cast iron top mount t3/t4 manifold
Enjuku Racing t3/t4 50 trim with .63 a/r

I also have a basic board with 2 SST reflashable chips 27sf512 I believe.

I have made countless changes, no matter what I do the car runs rich.

So I pinpointed several things that I believe is wrong and in no particular order:

1. FPR has gone bad (purchased a Megan Racing Adjustable FPR)
2. MAF is no good, can verify this with sofware such as NDS or ???
3. Timing is off, once again can verify this with NDS or Nismotronic ( I have a cable but once I start the car the cable is never able to reconnect)
4. Vacuum leaks (purchased some carb cleaner plan on testing prior to megan racing FPR install)
5. Idle air speed adjustment?


Any comments and or thoughts?
2011-08-16 20:24:15
#2
Originally Posted by Jybfan04

So I pinpointed several things that I believe is wrong and in no particular order:

1. FPR has gone bad (purchased a Megan Racing Adjustable FPR)
2. MAF is no good, can verify this with sofware such as NDS or ???
3. Timing is off, once again can verify this with NDS or Nismotronic ( I have a cable but once I start the car the cable is never able to reconnect)
4. Vacuum leaks (purchased some carb cleaner plan on testing prior to megan racing FPR install)
5. Idle air speed adjustment?


Any comments and or thoughts?


I am getting a new order of cables in next week if you still want to give one of those a try.

I haven't had a car that I couldn't connect to yet using the ECUtalk cable.

Once you are able to grab some accurate data you will be able to see what the car is doing.

BUT if you are able to log with the key on but with the engine off you will be able to see what the maf voltage is just with key on.. and this might be able to lead you to a conclusion if the maf has a wiring problem or not.

If all else fails you are also more than welcome to bring the car up so I can help you diagnose the problem!
2011-08-16 20:39:51
#3
Could the honda resistor box have the wrong resistance for the injectors? I had the same problem with a calum basic and ended up being one the chips was bad. Just throwing stuff out there, hope something helps! Good luck
2011-08-17 01:50:35
#4
BTW

I would like to give a big thanks to John aka Jktuning, dfdfdfd aka Dave @ tunercode and Vadim for all the information and help they have given me thus far.

Hey John,

I want to get tat cable soon as you have it in stock so if not this week, I will order it next week as well as a new set of chips to have on standby.
2011-08-17 03:58:03
#5
Originally Posted by Jybfan04


1. FPR has gone bad (purchased a Megan Racing Adjustable FPR)
2. MAF is no good, can verify this with sofware such as NDS or ???
3. Timing is off, once again can verify this with NDS or Nismotronic ( I have a cable but once I start the car the cable is never able to reconnect)
4. Vacuum leaks (purchased some carb cleaner plan on testing prior to megan racing FPR install)
5. Idle air speed adjustment?


Any comments and or thoughts?


1) If its a stock FPR normally they tend to be fairly sturdy. What fuel pump are you running?
2) MAF voltage can be checked by using a DMM and connecting it across the ground wire and a known ground source on the car. For a 300ZX MAF, it should be between 1.0 - 1.7 Volts at idle (if my memory serves me correctly)
3) Too much advanced timing and you will be running lean. The opposite occurs for Retarding timing. Check your base timing and make sure its within spec and go from there
4) Also check for boost leaks. Good vacuum should be right around 22 in HG. Anything lower than say 19 in HG, I would start checking for leaks (especially since you have stock cams).
5) The IAC wouldn't have much effect on how rich you are running (can someone back me up on this??). But worth a check regardless
2011-08-17 14:21:21
#6
In response to Boostlee questions below:

1) If its a stock FPR normally they tend to be fairly sturdy. What fuel pump are you running? *Walboro 255

2) MAF voltage can be checked by using a DMM and connecting it across the ground wire and a known ground source on the car. For a 300ZX MAF, it should be between 1.0 - 1.7 Volts at idle (if my memory serves me correctly) *I have to check with my DMM and or consult cable..


3) Too much advanced timing and you will be running lean. The opposite occurs for Retarding timing. Check your base timing and make sure its within spec and go from there * Something tells me my timing is off because it is running ridiculously rich


4) Also check for boost leaks. Good vacuum should be right around 22 in HG. Anything lower than say 19 in HG, I would start checking for leaks (especially since you have stock cams). * At idle its around 20 HG btw my cams aren't stock I have Brian Crower 264's in/ex
5) The IAC wouldn't have much effect on how rich you are running (can someone back me up on this??). But worth a check regardless
2011-08-21 16:56:09
#7
So I changed my FPR to an adjustable one, set it to 43.5, same results...

Runs rich high 9's low 10's...

Also, did a compression check of the motor and here were the results:

Cylinder 1: 150
Cylinder 2: 143
Cylinder 3: 140
Cylinder 4: 140

So at least I know the bottom end is fine, my next thing is to check cam timing to ensure the cams are dialed in properly..

I also still need to check my Maf, which I will do today as well to check Vacuum leaks with carb cleaner..

Any other suggestions?
2011-08-23 02:31:32
#8
I have a chance to get some MSD 50lb injectors, thinking those should be a bit more easier to tune..

Any thoughts?
2011-08-27 20:32:15
#9
So I purchased some 50 lb MSD injectors and set my fpr to 3 bar at idle with vacuum unplugged.

I've been fooling around with a few base maps and finally was able to get my car to lean out compared to my 75lb injectors that I have.

Car idles around 15 - 16 afr.. How ever my idle isn't steady and is kind of jumping all over the place.

It was getting kind of late last night so I called it quits...

Here is a screen shot of my fuel and timing maps.


Fuel Map



Timing Map
2011-08-27 23:35:24
#10
Have you tried to drive the car yet?

Try giving it a little more injector latency, that should help richen it up a bit at idle and lower throttle conditions.
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