Back in a skyline!! 2 Quick questions, hopefully simple answers.

[evolution23]

So finally got back into a skyline, picked up a 1994 GTS-25T with 91xxx km's. Car runs and drives great but i have 2 quick little questions.

1. If i turn the key and start it right away it takes about 2 seconds before it fires but if i give it a few seconds to let the pump prime the system it fires almost instantly, is this normal? (does have turbo timer, could this have anything to do with it?)

2. the car is running stock boost still but when the turbo spools up at WOT the car pops (backfires?) I stop immediately when it does this. If i ease into the pedal it doesn't seem to do it.

Could it be the pump is getting weak so it starts to lean out at WOT? I am going to take it to Monkey Nutz Racing tomorrow and see if they can help me out with this but just wondering if anyone knows or has any suggestions of what it could be. (plugs, pump, CAS, timing, etc..) previous owner said it started doing this after he removed the silencer in the exhaust and figured it was a stock rev limiter?

Thanks!!

Pic of the new skyline!

[evolution23]

just noticed the "fix your hesitation" thread, going to try some of those and see. Will post if i figure anything out

[mistercrow]

If your car would be running lean at WOT you wouldnt have backfires. I used to have the same problem on my car, hitting the highway and going WOT and hit a couple of backfires due to bad spark. I got myself some splitfires and never got the issue again.

[evolution23]

If your car would be running lean at WOT you wouldnt have backfires. I used to have the same problem on my car, hitting the highway and going WOT and hit a couple of backfires due to bad spark. I got myself some splitfires and never got the issue again.

thats something im for sure getting soon, was going to compare between yellow jacket and split fire see which one is the better preference. Then some new plugs gapped at .8 and get a boost controller to turn it up to 12psi. Ill see if Monkey Nutz can help me out tomorrow, i have a feeling it might be something simple like a vacuum leak.

[Skym]

1.) Normal. If have exhaust, ECU tune is out which doesn't help with cold startup. What happens when starting engine is one startup table is used on stock ECU during cranking that's fairly lean, then when release key stock ECU switches to a richer startup table which makes engine stumble.

2.) It's usually due to sparkplug gap being too wide if not on revlimiter. The result can be failed coilpacks (x2). It can be 4, 5th cylinder coilpacks and the other coilpacks are usually ok. The grey marks on both sides under mounting bracket on coilpack gives it away that coilpacks are leaking or testing them on the bench is another way.

About fuel pump, fuel pumps usually last over 100,000km. But if fuelfilter in engine bay or the sock filter in the tank is clogged, fuelpump can fail earlier. Change fuelpump out every 100,000km and change fuelfilter every 20,000km or less.

My advice with a second hand car would be to do a full service. Change fluids in diffhead, gearbox, powersteering, change fuel filter, change sparkplugs, change oil, oil filter, service aircon system (aircon specialist type of job who has the equipment to remove gas safely and refill with new gas, oil, check aircon pump, etc), change airfilter in stock airbox (or upgrade to podfilter with cold airbox around it), wiper blades, coolant system (change coolant, water, flush engine when cold or could crack the block, head and change thermostat with new stock thermostat), lube hinges on doors, hood, trunk lid, etc.

Also at 110,000km the cambelt, tensioner bearing, idler bearing, mounting bolt, cam, crank seals, waterpump need replacing.

Around 10-11psi with R33 RB25DET. Should run without problems at those boost levels with stock ECU tune.

If buy a Link or Vipec ECU (MAP sensor, so can remove MAF) + IAT sensor, boost control solenoid with full 3" exhaust from stock turbo, podfilter, 550cc injectors, 255-300lph fuelpump, upgraded single plate clutch (Nismo, Excedy, etc), it's not uncommon to extract up to around 386hp at engine with 10-11psi or roughly 322rwhp. For most that's enough hp for a street car.

[evolution23]

1.) Normal. If have exhaust, ECU tune is out which doesn't help with cold startup. What happens when starting engine is one startup table is used on stock ECU during cranking that's fairly lean, then when release key stock ECU switches to a richer startup table which makes engine stumble.

2.) It's usually due to sparkplug gap being too wide if not on revlimiter. The result can be failed coilpacks (x2). It can be 4, 5th cylinder coilpacks and the other coilpacks are usually ok. The grey marks on both sides under mounting bracket on coilpack gives it away that coilpacks are leaking or testing them on the bench is another way.

About fuel pump, fuel pumps usually last over 100,000km. But if fuelfilter in engine bay or the sock filter the tank is clogged, fuelpump can fail earlier. Change fuelpump out every 100,00km and change fuelfilter every 20,000km or less.

My advice with a second hand car would be to do a full service. Change fluids in diffhead, gearbox, powersteering, change fuel filter, change sparkplugs, change oil, oil filter, service aircon system (aircon specialist type of job who has the equipment to remove gas safely and refill with new gas, oil, check aircon pump, etc), change airfilter in stock airbox (or upgrade to podfilter with cold airbox around it), wiper blades, coolant system (change coolant, water, flush engine when cold or could crack the block, head and change thermostat with new stock thermostat), lube hinges on doors hood, trunk lid, etc.

Also at 110,000km the cambelt, tensioner bearing, idler bearing, mounting bolt, cam, crank seals, waterpump need replacing.

Around 10-11psi with R33 RB25DET. Should run without problems at those boost levels with stock ECU tune.

If buy a Link or Vipec ECU (MAP sensor, so can remove MAF) + IAT sensor, boost control solenoid with full 3" exhaust from stock turbo, podfilter, 550cc injectors, 255-300lph fuelpump, upgraded single plate clutch (Nismo, Excedy, etc), it's not uncommon to extract up to around 386hp at engine with 10-11psi or roughly 322rwhp. For most that's enough hp for a street car.

Alright the start up made me think it might be a fuel pump but you made that pretty clear lol, and yeah I'm about to start replacing filters, plugs, etc. The coolant looked pretty watery, engine oil kind of dirty so was going to for sure do both of those as soon as I can. Not looking to get much more power, mostly just want a really nice smooth idle and rev as there is already plenty of power with the rb25. I do however want a bit more boost, my old gts had 12psi and with this one running stock it feels like the turbo spools up and tops out too quickly, I want a bit longer duration. Other than that I am loving this car, definitely missed having a skyline.

Thanks for the extremely detailed post! Makes things simple to understand.

Maybe you would also know an answer to this, I can never seem to find any wiper blade that actually works good on a skyline, if tried reflex and normal type blades, they always seem to miss or streak but if I put them on like a Honda civic, they work fine. Any ideas? Thanks!

[Skym]

It makes it harder to start if starting engine while fuel pump is priming, but is not always the main cause if it happens after fuel pump primes. I found out after trying this and that, it can be due to running too thick oil (Changed to 10w40 on my car. Factory oil is 7.5w30, closest off the shelf is 5w30 or 10w30), ECU tune (as mentioned above). Also CAS on the way out is another cause, but makes it harder to start when engine is hot, cold. Also you are correct, intake airleaks don't help. Another trick I used was cranking engine longer via key which makes engine pump pistons more, that sucks more air into cylinders. Then let go of key and engine starts with a slightly less rich mixture.

As far as I know the top out problem is ECU dropping boost level via stock boost control solenoid.I think some fit RB20DET internal wastegate actuator (look on SAU forum). Or play with the boost control solenoid (look on SAU forum) so it produces the same boost level throughout.

I have the same problem and was told to check the window for wax (someone might have used wash n wax). A trick is to cut a potato in half, smear on window, wipe window with paper towl to clean the wax, etc off. Or use window cleaner (Bars Bugs or similar) which might take the wax off.

[evolution23]

It makes it harder to start if starting engine while fuel pump is priming, but is not always the main cause if it happens after fuel pump primes. I found out after trying this and that, it can be due to running too thick oil (Changed to 10w40 on my car. Factory oil is 7.5w30, closest off the shelf is 5w30 or 10w30), ECU tune (as mentioned above). Also CAS on the way out is another cause, but makes it harder to start when engine is hot, cold. Also you are correct, intake airleaks don't help. Another trick I used was cranking engine longer via key which makes engine pump pistons more, that sucks more air into cylinders. Then let go of key and engine starts with a slightly less rich mixture.

As far as I know the top out problem is ECU dropping boost level via stock boost control solenoid.I think some fit RB20DET internal wastegate actuator (look on SAU forum). Or play with the boost control solenoid (look on SAU forum) so it produces the same boost level throughout.

I have the same problem and was told to check the window for wax (someone might have used wash n wax). A trick is to cut a potato in half, smear on window, wipe window with paper towl to clean the wax, etc off. Or use window cleaner (Bars Bugs or similar) which might take the wax off.

Alright well I'll see if the shop can tell me anything, going to get everything checked out to see if I need to replace anything anyways. As for the window I thought since the cars 19 years old the glass may have warped slightly seeing as glass is not solid but I'll try cleaning the window off and see what happens.

Again, thanks!

[evolution23]

Had a couple air leaks including the BOV, had the plugs regapped and the car is now boosting great. It does have some random misses usually when idling or if you give it a tiny bit of gas while cruising along, I'm assuming this is just cause its got the original coil packs? Will be getting some splitfire's hopefully next week! Thanks for all the help!

[Skym]

The stock BOV flange can leak if someone removes, refits the stock BOV and doesn't replace the gasket. Airleaks are fairly easy to spot as rpm needle tends to go up and down more than usual on dash at idle, which is due to o2 sensor making ECU adjust A/F ratio leaner, richer, etc.

Missing at idle can be due to tune being out, o2 sensor, too thick oil, intake airleaks, TPS, coilpacks, etc. If unplug or disable o2 sensor it should stop the A/F ratio being adjusted (I wouldn't unplug o2 sensor without a wideband in exhaust to check A/F ratio, just incase engine is running too lean due to faulty fuelpump, clogged fuelfilter, etc and o2 sensor is preventing this from happening). If engine has done over 40,000km-60,000km (recommended km by Nissan to check, change o2 sensor) the o2 sensor, TPS needs replacing (usually not replaced by previous owners). Going by what you have told me with the off oil, don't think engine has been serviced properly.

From what I understand, TPS helps ECU to inject more fuel on top of what's on fuel map to stop engine going lean, hesitating when you suddenly press throttle (known as transient enrichment). If TPS is faulty, ECU could be running engine leaner or richer, depending on voltage from TPS. If leaner, can get a lean missfire when accelerating.

Coilpacks could be another cause if gaps were too wide on sparkplugs (need to test them on bench, check for the grey marks as mentioned above). Your meant to change coilpacks, sparkplugs, coilpack loom out every 100,000km. Alot of things need servicing around 100,000km+.

[evolution23]

The stock BOV flange can leak if someone removes, refits the stock BOV and doesn't replace the gasket. Airleaks are fairly easy to spot as rpm needle tends to go up and down more than usual on dash at idle, which is due to o2 sensor making ECU adjust A/F ratio leaner, richer, etc.

Missing at idle can be due to tune being out, o2 sensor, too thick oil, intake airleaks, TPS, coilpacks, etc. If unplug or disable o2 sensor it should stop the A/F ratio being adjusted (I wouldn't unplug o2 sensor without a wideband in exhaust to check A/F ratio, just incase engine is running too lean due to faulty fuelpump, clogged fuelfilter, etc and o2 sensor is preventing this from happening). If engine has done over 40,000km-60,000km (recommended km by Nissan to check, change o2 sensor) the o2 sensor, TPS needs replacing (usually not replaced by previous owners). Going by what you have told me with the off oil, don't think engine has been serviced properly.

From what I understand, TPS helps ECU to inject more fuel on top of what's on fuel map to stop engine going lean, hesitating when you suddenly press throttle (known as transient enrichment). If TPS is faulty, ECU could be running engine leaner or richer, depending on voltage from TPS. If leaner, can get a lean missfire when accelerating.

Coilpacks could be another cause if gaps were too wide on sparkplugs (need to test them on bench, check for the grey marks as mentioned above). Your meant to change coilpacks, sparkplugs, coilpack loom out every 100,000km. Alot of things need servicing around 100,000km+.

Hmm its kind of hard to explain, i know sometimes the car will stay revved at like 1500 rpm for a tiny bit longer, maybe a second. Or it will rev itself up to 1000 - 1500 rpm while idling (only happened once). Other than that, ill be sitting idling and there will be a random misfire it seems, then while cruising if i just barely tap the gas (not quite enough to cruise at a constant speed, in between cruising and coasting) the car kind of sputters. If i give it gas though it accelerated and drives nicely, theres just a very small sweet spot where it will sputter. And while shifting i get the occasional "pop" from the exhaust. Dont think this is anything major, going to slowly order some new parts over the next 2 months (splitfires, timing belt kit and water pump, FMIC, Boost controller, HKS Super Sequential BOV, stock BOV is still in place, had a second Blitz BOV by the air filter, both functioning properly but the Blitz one was leaking and Monkey Nutz Racing tried to repair it but could not stop the air leak so we took it off and welded a plate on for now) then changing all the fluids and filters, testing the fuel pump, then thinking about some slightly higher pressure injectors then a fresh tune on the ecu) I will look into the o2 sensor and TPS, clean the AAC, MAF, etc.. I would like to install a wideband gauge as well really soon. I want to get the pillar pod mounts and move the boost guage to the pillar and have a wideband gauge installed on the pillar as well.

Dont really want to go crazy with any mods, just want to get this engine running as smoothly as possible for better reliability and have a few things installed and changed or upgraded to help maintain this car!

[Skym]

The o2 sensor when faulty can make rpm needle go up and down alot at idle (up to 1500rpm). Also can be o2 sensor if engine is running too rich (popping sound from exhaust can be because of flames due to running too rich). Both can happen if o2 sensor is too slow to react to sudden changes in A/F ratio and makes ECU make engine stay rich or lean too long. Also could be a slight airleak on throttlebody as well (intake hose joiner has gone hard due to heat and doesn't seal properly) which when combined with what ECU does, can make revs rise for little while after slowing down, then settle.

Fitted a Synapse BOV which corrected alot of drivabilty problems, increased transient response.

With electronic boost gauge, best to have on opposite side of dash / speedo area (away from window on rainy days). Also A pillar pod blocks your vision.

[evolution23]

The o2 sensor when faulty can make rpm needle go up and down alot at idle (up to 1500rpm). Also can be o2 sensor if engine is running too rich (popping sound from exhaust can be because of flames due to running too rich). Both can happen if o2 sensor is too slow to react to sudden changes in A/F ratio and makes ECU make engine stay rich or lean too long. Also could be a slight airleak on throttlebody as well (intake hose joiner has gone hard due to heat and doesn't seal properly) which when combined with what ECU does, can make revs rise for little while after slowing down, then settle.

Fitted a Synapse BOV which corrected alot of drivabilty problems, increased transient response.

With electronic boost gauge, best to have on opposite side of dash / speedo area (away from window on rainy days). Also A pillar pod blocks your vision.

Never thought about it blocking vision. Always just thought of it being conveniently in sight but your totally right. Your like a skyline genius lol. As for the pop between shifting it only does it after I give it some gas like say I'm going to pass someone and need to put my foot into it a bit then I go to change gears and it will pop. I think you can run a manual scan to tell you if the cars running rich or lean? Stomping the brakes and turning the wheel back and forth or something?

[evolution23]

For some reason i do not have the "Edit" option for my post so ill post it here. Fixed air leaks, removed a leaking BOV, and regapped my plugs. Car runs a lot better now, still isnt running as good as it could though. I ran a manual diagnostic on my ECU i get code 11 which is my crank angle sensor. Im wondering if it isnt adjusted properly or if it needs replaced? And could this cause any of the originally posted problems? thats the only code my ecu is flashing.

Edit: (odd im able to edit this post but none others?) found an r34 manual, got the car into diagnostic mode like before, (i cleared the code so it is now flashing 55) started the car to put it into diagnostic mode 2, (car is warmed up already) held it at 2000 rpm, light flashes abou t 6 - 7 times while at 2000 rpm. (r34 manual says it should blink atleast 5 times during 10 seconds so im assuming this is good) then when i let it idle down to 700rpm it blinks 4 long blinks in about 10 seconds (manual doesnt say anything about testing while at idle so this should be irrelevant but thought i would post it as well)

SO im guessing my CAS is not adjusted properly? Theres a sticker that was across the top right bolt on the CAS and it has been torn so someone has messed with the CAS before.

[beacher1B0]

Find yourself the engine manual, also i believe there is a translated R33 service manual on the internet somewhere. Better than using the R34 manual.