New To The R32 With A Question.

[sponaugle]

Greetings,

I’m new to this forum, and recently imported to the US a Japanese 1990 R32 GT-R with about 70k km on the clock. As most of you know the US 25 year import limitations make these early R32s very attractive here in the states.

The R32 has a few modifications, as documented by the exporter:

BNR34N1 engine block

Tomei Camshafts

Tomei head gasket 1.2mm

Tomei turbine outlet

BNR34 Gold Brembo Brakes (Front and Rear)

BNR34 Turbos

BNR34 Injector

Mines VX-ROM ECU

Nismo sport clutch

KIT oil catch tank

copper two-layer radiator

RS-R muffler

harmonic drive nismo

Mines 320km meter

The body is in decent condition, especially for a 25 year old car. The interior is reasonable, but worn. I’m still determining what I am going to do, but I suspect I'll do a built block, a pair of GT3071s, A Vipec ECU, and shoot for 600whp (450kw) on E85. I'm curious to see what oil pump is on the car, since it appears the block was swapped for an R34N1 block.

Before my question, and since I have not posted before, a small introduction.

While I am new to the R32, I have a few other cars that are of the same flavor… and from what I saw on the roads in Australia they not far from the Australian enthusiast mark! I have an 08 STI with the usual Subaru stuff like a built block, Cosworth Heads and Cams, EFR7670 turbo, Cobb, Perrin headers, exhaust, etc. It makes ~480whp (360kw) on pump fuel.

I also have a 2002 WRX with a somewhat uncommon setup, as I swapped in an built EZ30R from the US Tribeca. It is a 3.0L 6 cylinder with a Garrett 35R turbo, custom manifolds and exhaust, Vipec ECU, built transmission and JDM STI drivetrain. It makes about 520whp(390kw) on E85, and is mostly a track car.

In even more Australian form, I have a 2006 Pontiac GTO ( aka Holden Monaro ) with a twin-turbo setup running 2 GT3071s. On the previous turbos I made bit over 620whp(460kw), but with the 3071s I should have no problem getting 750whp(560kw) once I get the fuel system finished.

Closer to the GTR territory, My daily driver is a 2014 R35 GT-R with some minor modifications; Replacement IHI7156 turbochargers (similar to the GTX2971R), ID1300s, Fully built PPG/Jacks Transmission, Cobb Downpipes and Midpipes, HKS Legamax Exhaust, 752whp (560kw).

(details: http://www.gtrlife.com/forums/topic/112120-2014-dyno-tuning-sbd8001000-flex-fuel-lots-of-data/)

All fun cars, built and calibrated myself.

Anyways, on the root of my question:

My R32 appears to have an interesting stumble. While driving the car everything runs great (Both full throttle and light load), but about 30 mins into a drive I have been getting a significant misfire event. It is enough of a misfire to keep the car from going much over 20 mph, and even in neutral the car has a hard time reving past 3k rpm. The onset is sudden, and in most cases it stays until I turn the car off and let it cool a bit. On a few occasions it has happened and gone away 20-30 seconds later. In all cases this is after the car is hot, and peak outside temperatures have been ~35C as well. It appears to be partially temperature related, and when it is not happening power delivery is very smooth.

I did research across many of the threads on this forum as well as a few others, and I can see a few different potential sources:

(1) An ignition problem – either bad coils, or a bad ignitor. Given the massive loss of power in what appears to be all 6 cylinders, I would tend towards the ignitor. Since I don’t know the history of the car, and the car is 25 years old, It would not be unreasonable that the ignitor is failing. After driving a bit the ignitor gets pretty hot sitting in the engine valley.

(2) A problem with the MAF sensors - This same kind of significant power hesitation could be caused by a very lean or very rich mixture, which could happen with a bad MAF sensor. This seems less likely, as there were occasions where the problem came and went over a very short period of time.

(3) A problem with the CAS sensors. - The siginificant of the misfire could be a result of the CAS sensor and ECU losing sync. There are backfires during this event, suggesting ignition occuring late in the cycle. I am not familiar with the rate of failure of the CAS sensor.

(4) A problem with the fuel system (injectors, fuel pressure regulator, pump, filter, etc). A possibility, however on the few occasions where the problem cycled on and off, it seemed very rapid both in rate of failure, and rate of recovery which seems like a poor match.

All of these are possible of course, but it would seem #1 is the first cause I would investigate.

To help diagnose, I removed the coils, spark plugs, and ignitor. The coils looked undamaged, and all measured 0.9 – 1.0. I replaced the plugs with new BCPR7EIX plugs gapped to about .8mm. When reinstalling, I left off the valley cover, and ziptied the ignitor to the strut tower brace so as to keep it a little farther away from the heat. Testing after this showed some improvement but the problem still occurred later in the day (perhaps after some heat soak).

As a test I brought along a can of compressed air, and used that the cool down the ignitor (turning the can upside down produces a very cold difluoroethane mix). That did seem to help a bit, however not as much as I would have expected, and not enough to convince me of the source.

So, any comments on my analysis? I could purchase new coils and a new ignitor as a starting point, and I have a consult 2 cable in route for further information collecting.

Cheers,

Jeff

Edited July 10, 2015 by sponaugle

[Hadouken]

Re solder afm. See if that does the trick.

[JH32]

To help diagnose, I removed the coils, spark plugs, and ignitor. The coils looked undamaged, and all measured 0.9 – 1.0. I replaced the plugs with new BCPR7EIX plugs gapped to about .8mm. When reinstalling, I left off the valley cover, and ziptied the ignitor to the strut tower brace so as to keep it a little farther away from the heat. Testing after this showed some improvement but the problem still occurred later in the day (perhaps after some heat soak).

As a test I brought along a can of compressed air, and used that the cool down the ignitor (turning the can upside down produces a very cold difluoroethane mix). That did seem to help a bit, however not as much as I would have expected, and not enough to convince me of the source.

I wouldn't have thought that the ignitor getting hot is an issue mate.

As Hadouken suggests, AFMs would be the next likely usual culprit - check the connections.

[sponaugle]

Re solder afm. See if that does the trick.

Interesting. Is it a common problem that the wire connectors into the MAFs have loose connections? That certainly is an easy task to do.. and with the consult II I could log the AFM voltages and see if one of them has a significant deviation. Of course temperature expansion can have a big effect on crimped connections, especially 25 year old ones.

I'll take a look at those connections. Thanks for the input.

Jeff

[sponaugle]

I wouldn't have thought that the ignitor getting hot is an issue mate.

As Hadouken suggests, AFMs would be the next likely usual culprit - check the connections.

Will do. I was surprised on how many threads (especially in the UK GTR forums) that mentioned bad ignitor caused by excessive heat and time. Since I am planning on switching to a Vipec/Link with speed density I'll be ditching the MAFS at some point anyways, but I'll dig into the AFM connectors and see if there is a problem there.

Cheers,

Jeff

[sponaugle]

Re solder afm. See if that does the trick.

I'm not sure how I didn't notice this thread earlier: http://www.sau.com.au/forums/topic/113284-fixing-your-rb26-afms/

My mistake. It outlines the AFM problem and resoldering, which I'll do right away.

Jeff