Chasing lean/misfire the last 6 Months. Built Longblock

[R3b]

Big wall of text but bare with me....

Been fighting this lean idle and misfire the last 6 months. This isnt my first time with ka-t, had a stock motor pushed 10psi on corn till one day it started knocking and bent two rods. Motor had about 160-200k miles. No biggie, go through a tear down, get a bunch of parts. Did a standard motor build with wiseco/manley setup bored out, crank balanced/polish, cometic HG with the head/block decked. Head was cleaned up with new guides/valve stem seals. Running RS rom tune, Martin is a legend! Have z32 maf and 1000cc injectors with precision t3 entry level turbo, tial wastegate, hks bov blah blah blah.

Issue is on start, basically cold the car would run seriously lean and stall out. I got it to idle now messing with the throttle plate and IACV screw but its reading --- on my wideband. Basically 17+ afrs. Now list of things i've tried and swapped out.

-Brand new iacv, had an early ka so had the single jingle connector and wouldnt fit my WS harness.
-Tried two different z32 mafs, good voltage on idle, ground is clean and is in a blow through setup. The housing leaks a little but all of them do on the cold pipe
- New nissan coolant temp sensor
- Tried 3 different tps and two different throttle bodies
- Vaccum tested/smoke tested about a million times. Holds 10-15psi like nothing. Did find a light leak on my ACC, the long skinny under the intake runners. Only see it because of bubbles from soapy water.
- Two new sets of bkr7e gapped at .30
- New cap for dizzy and NGK spark leads.
- Swapped a buddies dizzy and set up timing and no change.
- Brand new bosch o2 sensor s14 style. Its a 3 wire and fits the WS harness.
- five0 1000cc sidefeeds new (yes I know go topfeed) swapped those into my buddies car and loaded a stock rom tune with a regular resize and car idle perfect. I bought a moates chip burner and got a copy of nistune.
-Compression was goodish. I had 150 across besides cylinder 3 which was 120. Had similar compression on my stock motor and turns out my exhaust valve was leaking, was kinda warped along with one in 1st cylinder. No problem, got new BC valves, took off the head and my machinist swapped it in and redid the lash. Thought it was my fix but started the exact same. Check compression and leak down again. All checks out fine.
-Tried 3 different ecus, tried my old 720cc injectors and my buddies stock injectors. Same issue.
Checked brake booster line check valve, not leaking.
-PCV system is VTA to a baffled can, doubt an open fitting on block pcv port will cause it to run lean.
-Did timing a million times, at 20 with light and Nissan datascan and checks out in pictures. Will post later.
- replaced old e85 in the tank with fresh corn. Replaced that with 93 as of last week.
-Fuel pump is a walbro 255, works fine just super loud will replace soon. Swapped in a buddies one and no change.
-New tomei FPR, fuel pressure changes on idle because of how lean it is and terrible vaccum but on key its dead at 3 bar (43psi) was maybe thinking air in the system???? Is it possible to have correct fuel pressure but air in the system?

Here are some videos, one point thought it was the tune and injector latency but nope. Also got it to run rich but still lean on cruise by just doing a resize and maf change on stock tune. Turns out the TTP Min setting is a lot different than Martins tune and the ones I found on here. I doubt tuning can fix this since it runs lean no matter how much I increase the k value. A stock k value on 1000cc which are 3 times the size should not be running lean....

https://www.youtube.com/watch?v=qBbVtNIp5iQ the normal startup, gets worse when bringing the idle screw down and messing with the little nut for the throttle plate.

https://www.youtube.com/watch?v=tvrT4-q70Tg injector latency was pretty low at 650ms on the tune. Bumped it up to 800 and even a 1000 in the video and no change.

https://www.youtube.com/watch?v=YFSLPaKEZvM stock tune with resize/maf change. When I compared the tunes besides tables and k value the only difference was some cold start start up settings and TTPMIN/TTPMax settings. Trail and error I found it was the TTPMIN setting basically forcing the injectors to dump more fuel. It leans out right away with light tap or on cruise.

https://www.youtube.com/watch?v=ehZMTwI_LPQ This is what its like right now with the new valves sealing and 93 in the tank. With 02 on it dies out, without it and opening the throttle a bit and adjusting tps/ idle scew it can idle 1000-1500 easy but still lean and misfires.

[R3b]

Some pictures of this POS. Im 20, this is my first car and spent way too much time/money on this thing. I love it and have gone pretty far with myself and my dad but im out of ideas . If you want to see more I post a lot of it on instagram @ ihatemy240


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This was a before, it was such mess....

[R3b]

Bumppppppppp

[Jefro240]

Misfire wise you can try playing with the Plug Gap to see what happens. Go down to .25 or even .20 and see if it changes anything. It's a quick & simple test.

[R3b]

Its a lean misfire. Even with bkr7es I have at .28 it shouldnt misfire. Plus a spark related issue would results in a rich condition because fuel isnt being burnt right. Im shooting for 400 on stock ignition so only if I get blow out in boost is when I'd mess more with gap.

[R3b]

Bump, got the car idling and not stalling out by messing with the throttle plate adjustment nut and IACV screw. Will richen up a few afrs for a bit when I switch on my fans or change the temp in nistune/NDS but eventually when the car is warm will lean out again.

I'll try go back to tuning since car is somewhat idling. Its lean on idle and holding revs at 2k rpms. It will richen up on my wideband if I blip the throttle.

[jedi03]

fuel pump hard wired in?

[KAT-PWR]

Does nistune have a voltage correction factor? The added draw on the electrical system may cause the injectors to have a weaker pulse. Often times there are electrical compensation values to correct this.

[R3b]

Originally Posted by jedi03

fuel pump hard wired in?

yes sir, did the normal relay setup and battery is in the back. Still on the stock system for the signal wire.

As for nistune there is but I forgot the term for it. There is injector adjustment on voltage but what I see on my fan controller which also has a voltage gauge bult in, im getting 14v on idle and high 12s if I remember on NDS in the overall gauge view.

Was suspecting draw but its so minimal. It will richen up a few tenths in the afrs to go to high 17s but after more idling it leans out more which there is audible difference when there on but still super lean and way off my wideband.

[p00t]

There is a lot going on here so I may have missed something...

Verified timing chain is on there correct? I know you took the head off but you have two chains to deal with. Low vac on stock cams is often because one of the chains is off a tooth.

Have you tried disconnecting the MAF just to see how it runs? You have to start it twice without cycling the key to off with the MAF unplugged. I am not sure if there are any tight bends in the piping before/after the MAF (which is going to F-you).

If all that checks out look at your tune. Specifically the balance between latency and K value. What are you using? For idle that is lean keep increasing the latency. I don't care that you think 1ms of latency or what you have is too much, if it is lean keep increasing!

Once that is idling in the neighborhood of 13-14AFR then work on your K value. and keep going back and forth until you are happy. You will likely have to deal with a richer idle so that you are good in cruise and boost. Stock injectors are very linear in how they behave, as you go bigger the low pulsewidth stuff is just shitty.

Also before you change anything else in the tune TURN OFF O2 FEEDBACK. It has never worked right for me with bigger injectors.

[R3b]

Originally Posted by p00t

There is a lot going on here so I may have missed something...

Verified timing chain is on there correct? I know you took the head off but you have two chains to deal with. Low vac on stock cams is often because one of the chains is off a tooth.

Have you tried disconnecting the MAF just to see how it runs? You have to start it twice without cycling the key to off with the MAF unplugged. I am not sure if there are any tight bends in the piping before/after the MAF (which is going to F-you).

If all that checks out look at your tune. Specifically the balance between latency and K value. What are you using? For idle that is lean keep increasing the latency. I don't care that you think 1ms of latency or what you have is too much, if it is lean keep increasing!

Once that is idling in the neighborhood of 13-14AFR then work on your K value. and keep going back and forth until you are happy. You will likely have to deal with a richer idle so that you are good in cruise and boost. Stock injectors are very linear in how they behave, as you go bigger the low pulsewidth stuff is just shitty.

Also before you change anything else in the tune TURN OFF O2 FEEDBACK. It has never worked right for me with bigger injectors.

Timing looks good to me but now im second guessing myself looking at other pictures. I made sure to lock up my lower timing when I sent out my head for new valves. When I got it back did upper timing and basic head stuff all over again and car ran the exact same way.

The low vac is gone after messing with tps/throttle plate/iacv it now idles with good vac at 20ish but super lean like before. I tried disconnecting the maf and it instantly richens up. Swapped in two good know z32 maf and my piping is solid. Ran perfect when I was stock motor for 3k miles daily driving.

Tune wise I've cracked latency to 1200ms and no change in idle afrs and when holding revs it leans out still. I tried messing with k value and gone higher than the stock value which in theory should be dumping 3x as much fuel with my 1000cc if the value is the same as the 270cc. Still lean on idle and holding revs, in the tune as well i've turned off o2 feedback as well so thats all good.

Going to try revist timing. To me it looks fine but could be off a tooth on the lower because other pictures the exhaust exhaust lobe thats pointed up in cylinder 3 sits straight up while mine is a smidge to the left. The yellow bottom link is at the lowest point while in mine its a little bit to the right of the sprocket.

[p00t]

I would hate for you to take the front cover off to check. I think you can keep rotating the crank until the idler mark will hit the colored mark and then bring it to the 0 degree timing mark on the pulley. The idler sprocket dot should be on the chain mark then.

Try the maf thing too. Having so much fuel in your tune and not seeing any effect is concerning to me. But you said you tried different ECUs right? Not just tunes? The injectors are plugged in in the right order?

[R3b]

Is my lower timing off? AFAIK the idle sprocket dot should be five links from the guide on the right. On the fith link should be in the middle.
First picture is at TDC, second is 5BTDC, and third is a picture from a thread fixing incorrect lower timing without taking off the front cover. Cam timing looks perfect.

[p00t]

Originally Posted by R3b

Is my lower timing off? AFAIK the idle sprocket dot should be five links from the guide on the right. On the fith link should be in the middle.
First picture is at TDC, second is 5BTDC, and third is a picture from a thread fixing incorrect lower timing without taking off the front cover. Cam timing looks perfect.

I am not familiar with checking the chain that way, so if you trust the info then we can scratch that off the list. My thinking is that any difference in slack could put yours at a different spot than that picture.

In the second photo it looks further advanced so did you mean 5°ATDC? or are the pictures reversed versus your description?

If the chain is OK, you can run a quick check on the injectors:
-Unplug the harness to the coil
-Disconnect the injector rail from the intake manifold and prop it up so the injectors shoot horizontally.
-Connect the harness to the distributor.
-Turn the key to run and spin the distributor cog, look at the dist cap to know the direction to spin it.
-The injectors should all spray similarly and in the correct sequence 1-3-4-2.

[KAT-PWR]

Releasing the upper tensioner causes the chain/cam/idler position to move.

[R3b]

Originally Posted by p00t

In the second photo it looks further advanced so did you mean 5°ATDC? or are the pictures reversed versus your description?

If the chain is OK, you can run a quick check on the injectors:

Already know the injectors fire and took off the rail and spun the dizzy to see.

As far as 5 ATDC thats not right. On the crank you have the little timing marks. First picture is on the second mark going from left to right. The second picture is at the first mark on the crank

just like in this picture

[R3b]

Originally Posted by KAT-PWR

Releasing the upper tensioner causes the chain/cam/idler position to move.

I've taken it off about 4 times now to do the top cam timing and everytime from what i've noticed the sprocket links havent moved and car ran the exact same.

If it does cause it to move then how do reset the sprocket without taking off the pan, crank and front cover? Didnt you just finish the spare motor? Im sure you can reference either one of the pictures I posted.

[p00t]

Advanced was a poor choice of words. I mean the crank was turned more CW by the look of the chain. So if the first picture was TDC the second was 5ATDC.

[KAT-PWR]

Originally Posted by R3b

I've taken it off about 4 times now to do the top cam timing and everytime from what i've noticed the sprocket links havent moved and car ran the exact same.

If it does cause it to move then how do reset the sprocket without taking off the pan, crank and front cover? Didnt you just finish the spare motor? Im sure you can reference either one of the pictures I posted.

You chains looks fine

Also seal up the maf

[R3b]

Yes then you are right so im guessing timing is off 100%. If im getting "TDC" marks at 5BTDC then im off a tooth on my sprocket. Look at all these other pictures and you can see theyre half way. Im 90% most of these are at TDC since the posters on the threads I got them from just did there timing so im assuming the motor is still at tdc for them.









Even checked the fsm diagrams and its the samething, at TDC its 5 marks with the last on by the guide with half of it below it. EM-17 if you want to check.

[R3b]

Originally Posted by KAT-PWR

You chains looks fine

Also seal up the maf

I sealed it up with expoxy and no change. My old one was sealed up top to bottom and ran the same way. Even with this new one that is basically untouched it leaks just a tiny bit.

[KAT-PWR]

I'll try and dig up some pics tonight

[p00t]

I looked through those pictures (thanks for linking them). And I am going to say you are fine. The 5th link top pin would be touching the top of the tensioner if you were off a tooth. Everyone is going to see TDC differently depending on how your look at the pin on the front cover, and everyone is taking a shot from a different angle. Kind of need to average them all haha.

Further ideas:

Clamp off brake booster line, could be a big leak if the diaphragm is torn.
Clamp off PCV line in between the manifold and PCV (sanity check)
Max out TTP MAX settings in the tune, TTP MIN can only make you RICHER, check over as much as you can.
Any codes? If you watch the ECU flags while running does the start switch indicator go to off after starting?

[hanzbrady]

Did you try setting it to Wumbo?


I'm not here to help at all Nistune and KA's are something I'm not familiar with at all haha.

[R3b]

Originally Posted by p00t

Clamp off brake booster line, could be a big leak if the diaphragm is torn.
Clamp off PCV line in between the manifold and PCV (sanity check)
Max out TTP MAX settings in the tune, TTP MIN can only make you RICHER, check over as much as you can.
Any codes? If you watch the ECU flags while running does the start switch indicator go to off after starting?

Already blocked the booster line, my brakes do feel spongey and I just redid my lines/fluid so maybe it has a small leak but when I blocked it I had no change. I already blocked the recirculating pcv stock system and just have straight lines off the box and valve cover to a catch can.

The TTPmax is maxed out and TTP MIN when I leave it stock runs pretty rich but soon as I touch throttle it leans out completely on cruise.

Ecu have 0 codes, have to check the start indicator though.

[R3b]

Originally Posted by hanzbrady

Did you try setting it to Wumbo?


I'm not here to help at all Nistune and KA's are something I'm not familiar with at all haha.

Nah not yet but ill try.

Im sure my issue is something stupid small since ive looked at EVERYTHING at this point.

[R3b]

So an update is I took my dizzy out and realigned it. Looks like I was off a tooth everytime I put it in, I thought the metal part that spins was supposed to point toward the bolt hole and NOT turn as it went it. Looks like your supposed to line it up with that then it turns a bit upwards closer to the dizzy plug and sit right under the spark #1.

So knowing that when I did my timing I got 20 degrees when it was a tooth off and now when I time it with it in right im getting 15 degrees with a timing light and the dizzy fully turned to the right.

So with the dizzy right and I cant get my base idle to 20 then my lower timing is def off. Going to see if I can adjust it without pulling the whole bottom cover.

The car sounds loads different, sounds like it has a mean lope to it and can feel the engine have more go with it bogging out and shaking the car.

[R3b]

Another update, looks like my lower timing was off half a link...

Took off the whole front cover assembly, redid it and slapped the crank pulley on. At TDC on the crank I 100% get that half a link!

Im guessing when I was putting on the tensionor the left side of chain had some slack when I was doing the longblock and the chain moved over a link. So note to self is keep the marked side of the chain under pressure the whole time.

Will post pictures up later tonight. Hopefully I get a good start, seeing it line up now looks to be my issue. All goes good will be driving just before the 1 year mark when I took the car apart.

[R3b]

Disregard everything posted. Timing was fine, put the car back to stock still had the lean issue. On a whimp bought a bigger fuel pump since my 255 walley was getting annoying with its whine.

Got a 450, slapped it in and is 10x quieter and no more lean issue. So note to anyone is never let a 255 sit with corn for a few months. I had proper stock fuel pressure on my tomei fpr and yeah. Not idea it would be that since besides fuel pressure I wouldnt know what else to check.

So happy it was that and filled up and drove the car in just over a year feels like a new car doing an overhaul on everything.