89 GT-R electronic questions, no acceration

[Jolendd]

I GUESS IF ONE READS CAREFUL WE ALL MIGHT UNDERSTAND BETTER, I AM REPOSTING WITH ADDED INFO.
Sept 25 - Update: The problem with the erratic running/rich idle and lack of acceleration repairs itself often, seems to be related to length of time driven and how hard? bumps? heat? unknown.
If you shut the vehicle off for 1 minute or less and restart the problem comes back right away! Unable to determine what makes the problem return. ???? Any more takers, attempting to get a scan from local Nissan dealer if they can help.

Being a mechanic for over 30 years who mostly built American hot rods, (Big block Chevell’s etc. I recently became involved in my son's 89 GT-R BNR32 twin turbo "Godzilla" car. Wanting to learn as well as become more knowledgeable about these great cars. The engine appears to be 99% stock. Have engine and data plate pics available.
He just had the OEM turbo's replaced with equivalent used models for now. Old one's blew the exh impeller out the tailpipe and made lots of sparks on the highway. Neato
1. For awhile now the car when cold does not want to accelerate from idle. Serious hesitation and a rough low idle after warming up for long periods it will improve and run/idle smooth and take off like a rabbit. Problem was there before the turbo issue, has progressively gotten worse.2. The idle is rough and poor until this problem somehow occasionally/mostly corrects itself, try to drive it and it won’t pull a fat girl on a skateboard. Hit a bump sometimes and it takes off like a bullet. Shut off car for two mins or so and problem usually returns
3. Have done the basics, new plugs, new gas filter, checked and cleaned lots of wiring plugs and connections etc.
4. Car runs so rich I am afraid you could light the tailpipe and have a neat flamed exhaust like a nitro car.
Q1. A question is can these cars be scanned for engine codes?
Q2. Or are there diagnostic codes/blinks via any lights?
Q3. I am thinking something like the TPS (throttle pos sensor) I have not removed it or attempted adjustment yet.
Q4. Or possibly an air flow sensor, fuel pressure regulator, O2 sensor? computer problem or connection(s) to engine, corroded and or dirty wiring plugs to the engine, loose grounds? power wires.
Any suggestions would be great.

[bobbo]

You can scan them using Nissan CONSULT available at your local dealer and usually charge an unreasonable $99.00. I do recommend it as it can fill in some blanks as to what the car is doing. If you have MAF problems (common), o2 sensor problems and any of the other issues we see in a 20 year old car.
I highly suggest you down load a service manual. PM me if you have difficulty findin one online.
Welcome to the world of cars that use computers and fuel injection vs. controlled fuel leaks

[Jolendd]

I would appreciate a link or ?? for a service manual in English...lol

I have not searched for one yet.

[Jolendd]

I am very familiar with codes and electronics, what you dont think squirting raw gasolene down the intake with a squirt bottle with 4 butterflys is a precise method of fueling an engine. Rarely get lean problems.....lol Enjoyed your comment.......I also play with LPG power rods as the fuel is 140 octane and easy to regulate..


take care

[NoLimit0596]

two first common problem the mass air flow doesn't work correctly because solder was broken and make intermittent contact or the cas timing was way off but 90% of the time is bad solder in the maf


Also check this tread for ecu fault code

http://forums.gtrcanada.com/diys/2189-%2Ainfo%2A-checking-your-skyline-its-ecu-fault-codes.html

[MattiasJacobs]

Yep, should start with the mafs. Easiest way is find someone local with Working ones and test those. I would let the car warm up before accelerating hard. If its too rich get nistune installed and have it tuned. Fsm tells all. You can find it on www.gtrpwr.com

[Skym]

Rich can be due to lazy o2 sensors (stays rich longer). Unplug them (ECU uses preset voltages and ignores o2 sensor input), so can tell straight away if it's them. But it's recommended to check A/F ratio afterwards incase it's compensating for intake manifold gasket leak, weak fuelpump, etc. Also can do this with MAF's, TPS (stock ECU only features).

Usually you would hold throttle at 2000rpm and note how long it takes o2 sensor to switch between lean, rich and rich, lean on oscillioscope, Nissan's Consult (hand held diagnostic computer), Nistune tuning software or similar.

TPS is a electronic version of an accelerator pump on a carb engine. It affects transient throttle enrichment and prevents engine going suddenly lean and hesitating when throttlebody suddenly opens.

Translated english manuals can be bought here -

http://www.jpnz.co.nz/

[markdett]

9 times out of 10 if your huffing black smoke (running very rich), sounds like an AFM issue.

[MarusGTR]

I'd be on the MAF bandwagon, the problem they're referring to is on the board itself, not the external wiring. This would need you to source another MAF to troubleshoot. Note that the top MAF has a different board than the lower MAF (something that a lot of people seem to miss).

Here's the most recent version of the manual: http://forums.gtrcanada.com/faq/36-h...tml#post467565

Also, guys like Skym (lol) like to forget about people like us that don't have the troubleshooting equipment. The car has it's own diagnostic built in the ECU, like OBD, but it's read from a light on the ECU itself. The ECU is under the passenger (left side) kickplate. You can also read your mixture from the ECU light. The procedure can be found online but I have an excel sheet with all the info if you're stuck.

EDIT: It's refreshing to see a new member posting coherent threads...

[Jolendd]

Thanks for the input, Will do my best to chk the MAF(s) - I assume you mean the solder on the boards themselves? I understand that because of twin turbo - meaning twin air intakes means two DIFFERENT MAF's ?

What is cas timing? Cam advance system ? new term to me?

[Jolendd]

If its too rich get nistune installed ? What is nistune? Fsm tells all What is Fsm?

[Jolendd]

Thanks for the reply, most info I am very familiar with already.

Rich can be due to lazy o2 sensors ? Why would it correct itself on occasion? Bad O2 usually stay bad? I do not have a sniffer/gas analizer readily avail to check mixture, but trust me I could light it! I am very familier of how to monitor & check O2 switching from lean/rich. But have to be able to hook up my $8000 Snap On scanner first!.

Also can do this with MAF's, TPS (stock ECU only features). Nistune tuning software or similar.

TPS is a electronic version of an accelerator pump on a carb engine. Being a trained mechanic I am Very trained in how a TPS (POT) works, it is a potentialmeter! And also know that MAF are a weak link in many older electronic cars.

[Jolendd]

Dbl thanks for the refreshing coherent reply Would love your excel sheet when you have time to send/link it to me.

[Skym]

Nistune -

http://www.nistune.com/

Also, guys like Skym (lol) like to forget about people like us that don't have the troubleshooting equipment. The car has it's own diagnostic built in the ECU, like OBD, but it's read from a light on the ECU itself. The ECU is under the passenger (left side) kickplate. You can also read your mixture from the ECU light. The procedure can be found online but I have an excel sheet with all the info if you're stuck.

Used to check it that way (alot of hassle pulling ECU out to do that, as can screw up mounting screws, etc) or via going to Nissan dealership to use Consult, via Oscillioscope, multimeter at autosparky. But now I use Nistune tuning software, Consult cable (supposedly can't use Nissan's Consult anymore when have Nistune installed), as it's alot easier to check for sensor, etc faults yourself (can datalog sensors, monitor what ECU is doing in realtime, etc) and cost's me nothing to check. Also that diagnostic screw on side of ECU can sometimes be damaged.

[Skym]

Thanks for the reply, most info I am very familiar with already.

You're welcome. Oh, ok.

Rich can be due to lazy o2 sensors ?

On ECU the run rich software voltage trigger is set just before 0V (lean) and run lean software voltage trigger is just before 1V (rich). When o2 sensor fails (fouled by exhaust gasses) it starts to become lazy / slower to fluctuate between the rich, lean software voltage triggers, thus it can make ECU make engine stay rich longer (takes o2 sensor voltage longer to reach the software run lean voltage trigger). As you probably already know the time it takes o2 sensor voltage to switch between the software voltage triggers is what you check. Engine manual has how many times it switches between lean, rich voltage triggers in set amount of time.

Why would it correct itself on occasion?

Do you drive car on motorway???, as sometimes that helps it to correct itself, clean sparkplugs, etc.

When o2 sensor is really suffed it can make ECU make engine rich most of the time (pop flames from exhaust), rpm goes up (lean) and down (rich), etc.

Bad O2 usually stay bad?

Once o2 sensor is fouled it's stuffed and needs too be replaced. Some say they can clean them (learnt how to when done mechanics course), but I think new is better. They are NTK/NGK brand with Nissan logo on them.

Can buy NTK/NGK o2 sensors here -

http://www.kudosmotorsports.com/catalog/ngk-ntk-lambda-sensor-oxygen-ntk-nissan-skyline-r32-gtr-rb26dett-p-1024.html

Genuine Nissan o2 sensors -

http://www.kudosmotorsports.com/catalog/nissan-lambda-oxygen-sensor-front-genuine-nissan-skyline-r32-gtr-rb26dett-p-183.html

http://www.kudosmotorsports.com/catalog/nissan-lambda-oxygen-sensor-rear-genuine-nissan-skyline-r32-gtr-rb26dett-p-184.html

I do not have a sniffer/gas analizer readily avail to check mixture, but trust me I could light it! I am very familier of how to monitor & check O2 switching from lean/rich. But have to be able to hook up my $8000 Snap On scanner first!.

Don't need a wideband up tip of exhaust to check A/F ratio. Just check the voltage of each o2 sensor via oscillioscope, Nistune tuning software, Nissan's Consult, use diagnostic screw on side of ECU (consult engine manual on how to do this), etc.

With RB26 you have 2x o2 sensors and from what I have learnt, ECU takes the middle ground between the two o2 sensor voltages (same with MAF's) to get the correct voltage. When you run GTR ECU on GTS engine you can join those wires together to get one signal for one MAF, one signal for o2 sensor. You'll need to test both o2 sensors to figure out which is the cause.

TPS is a electronic version of an accelerator pump on a carb engine. Being a trained mechanic I am Very trained in how a TPS (POT) works, it is a potentialmeter! And also know that MAF are a weak link in many older electronic cars.

Oh, sorry, my bad.