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l28et s30 swap bad sputtering


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watch the video and let me know what this could be. its bad in first and second especially then 3rd is clean for the most part. this is wot first and second.i cant see to see the video so if you have trouble im sorry.

just copy paste the link. thanks

 

Edited by 240z7273
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i have a innovate afr guage. and it dose jump from 16-22.4 (max lean when its doing this. i belive its fuel related. ive gone threw a ton of sensor test and ignition stuff puls all the basics. im getting a fuel pressure guage tomorrow and will do an on road test with it..i think im going lean on low speed accell..but when im cruzing im chill at 12 13 afr...idols at 14-16. will report on it tomorrow i belive its fuel though...thnaks for the reply

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Watching this thread, b/c i have a similar issue. Car starts right away, idles at 600rpm super smooth, and cruises great; but at WOT it goes extremely lean, 16:1 and worse.

I saw in your other thread you mentioned disconnecting the CHTS to get it to run in closed loop, but when i tried that, the car died. Plugged it back in, and it idles perfect again.

 

My car has stock ecu and electronics, stock turbo injectors (i believe anyways, PO did the swap -- is there any way to tell the difference between NA and Turbo injectors visually?)

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Its hard to tell the difference in injectors becasue a lot of them have been replaced, with aftermarket ones. Those can be all different colors. If my memory serves me correctly, stock turbo injectors are brown.

 

Check the fuel filter also, Remove it and try to blow through it. You should be able to blow through the filter with no effort. If it takes a lot of effort to blow through it, it is clogged or clogging up. Replace it.

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Its hard to tell the difference in injectors becasue a lot of them have been replaced, with aftermarket ones. Those can be all different colors. If my memory serves me correctly, stock turbo injectors are brown.

 

Check the fuel filter also, Remove it and try to blow through it. You should be able to blow through the filter with no effort. If it takes a lot of effort to blow through it, it is clogged or clogging up. Replace it.

 

Thanks -- in my case at least, I have a brand new fuel Russell fuel filter -- replaced all the fuel lines firewall foward with braided lines as well as the stock filter (russell inline filter) and stock fpr (aeromotive adjustable fpr).

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ya im running stock injectors they are brown tops. Update on the progress: i did an on road fuel pressur test and it was solid at about 35-45 psi during the sputtering. then i hooked up my timing light and held the switch down and went for a run..during the sputtering it was blacking out. pulled the cap and the pin that feeds the roater was missing and the spring was contorted. so now i belive it is ignition. i want to do away with the cap and roter setup. i want DIS. waiting of a cap and roter but will up date when i get them on and go for a ride

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  • 2 weeks later...

ya im running stock injectors they are brown tops. Update on the progress: i did an on road fuel pressur test and it was solid at about 35-45 psi during the sputtering. then i hooked up my timing light and held the switch down and went for a run..during the sputtering it was blacking out. pulled the cap and the pin that feeds the roater was missing and the spring was contorted. so now i belive it is ignition. i want to do away with the cap and roter setup. i want DIS. waiting of a cap and roter but will up date when i get them on and go for a ride

 

 

Get a chance to troubleshoot again yet?

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Update: cap and roter installed. Along with new ignitor. Still boggs out. Noticed when i changed out my eastegate spring and held my throttel at about 5psi it pulls hard and steady. But i havent done any hard launches or even aggressive ones yet. My boost controller so will be here today so i will update asap.

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Watching this thread, b/c i have a similar issue. Car starts right away, idles at 600rpm super smooth, and cruises great; but at WOT it goes extremely lean, 16:1 and worse.

I saw in your other thread you mentioned disconnecting the CHTS to get it to run in closed loop, but when i tried that, the car died. Plugged it back in, and it idles perfect again.

 

My car has stock ecu and electronics, stock turbo injectors (i believe anyways, PO did the swap -- is there any way to tell the difference between NA and Turbo injectors visually?)

Disconnecting the CHTS does not put the ECU into 'closed loop'. Closed loop is achieved when the ECU is sampling all the major sensors + O2 sensor. During 'open loop' operation the ECU is not monitoring the O2 sensor/s and is basing its timing and fuel information off per-programmed maps. Unplugging the CHTS does put the ECU into open-loop operation until the sensor is plugged back in and a reasonable signal is read by the ECU. By unplugging the CHTS you are tricking the ECU into thinking the engine is very cold. Matter of fact -40*F. What that does is puts the ECU into cold enrichment and the fuel injectors are modulated pig rich!

 

ya im running stock injectors they are brown tops. Update on the progress: i did an on road fuel pressur test and it was solid at about 35-45 psi during the sputtering. then i hooked up my timing light and held the switch down and went for a run..during the sputtering it was blacking out. pulled the cap and the pin that feeds the roater was missing and the spring was contorted. so now i belive it is ignition. i want to do away with the cap and roter setup. i want DIS. waiting of a cap and roter but will up date when i get them on and go for a ride

 

Your fuel pressure sounds good.

Your ignition issue is bothersome. Question: Does this car sputter at all times or just when its warm?

Make sure your not seeing the timing jump around at 2000rpm idle. A few degrees is probably okay, but if your seeing it go all over the place Id suspect the CAS. IF you can get the engine to sputter with no load(high idle) I personally would start leaning harder on the timing issue, though that is not a 100% indicator of that failure.

 

 

Update: cap and roter installed. Along with new ignitor. Still boggs out. Noticed when i changed out my eastegate spring and held my throttel at about 5psi it pulls hard and steady. But i havent done any hard launches or even aggressive ones yet. My boost controller so will be here today so i will update asap.

 

Perhaps test the diaphragm in the old waste-gate? Make sure it isnt blown out.

I would not up your boost until you have sorted your current issue if that isnt obvious.

I can tell you from experience running the car like you are in that video will result in broken piston skirts galore in short order! They will stress crack up the sides of the skirts and possibly break the ring lands out between the rings.

 

So verify your timing and timing curve is solid not just base timing. Eliminate this possibility as this failure will cause exactly this issue!

IF timing is not the issue then verify that you have rock solid boost in stock range.

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  • 2 weeks later...

I replaced a few ignition items. With some improvement. Still not perfect. Decided to sell the car. Going LS1. Kept a few goodies. The car actually sold to rayaapp. He lives local and were worked out a sweet deal. I will miss the turbo z. Goodluck on your issue. Id go over your ignition very well. Then move on to fuel. Dont jump around.

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Disconnecting the CHTS does not put the ECU into 'closed loop'. Closed loop is achieved when the ECU is sampling all the major sensors + O2 sensor. During 'open loop' operation the ECU is not monitoring the O2 sensor/s and is basing its timing and fuel information off per-programmed maps. Unplugging the CHTS does put the ECU into open-loop operation until the sensor is plugged back in and a reasonable signal is read by the ECU. By unplugging the CHTS you are tricking the ECU into thinking the engine is very cold. Matter of fact -40*F. What that does is puts the ECU into cold enrichment and the fuel injectors are modulated pig rich!

 

Should the car still run with it unplugged though? Mine just dies

 

 

Your fuel pressure sounds good.

Your ignition issue is bothersome. Question: Does this car sputter at all times or just when its warm?

Make sure your not seeing the timing jump around at 2000rpm idle. A few degrees is probably okay, but if your seeing it go all over the place Id suspect the CAS. IF you can get the engine to sputter with no load(high idle) I personally would start leaning harder on the timing issue, though that is not a 100% indicator of that failure.

 

Perhaps test the diaphragm in the old waste-gate? Make sure it isnt blown out.

I would not up your boost until you have sorted your current issue if that isnt obvious.

I can tell you from experience running the car like you are in that video will result in broken piston skirts galore in short order! They will stress crack up the sides of the skirts and possibly break the ring lands out between the rings.

 

So verify your timing and timing curve is solid not just base timing. Eliminate this possibility as this failure will cause exactly this issue!

IF timing is not the issue then verify that you have rock solid boost in stock range.

 

Just bought a timing light yesterday so I can check this. Previously just borrowed a buddy's but only set base timing.

 

I still have the stock turbo/wastegate, and boost gauge is dead on at 7psi at WOT, so not a lot options left. I'll check my timing curve and see whats what.

 

 

I replaced a few ignition items. With some improvement. Still not perfect. Decided to sell the car. Going LS1. Kept a few goodies. The car actually sold to rayaapp. He lives local and were worked out a sweet deal. I will miss the turbo z. Goodluck on your issue. Id go over your ignition very well. Then move on to fuel. Dont jump around.

 

Thanks for the headsup, hopefully rayaapp can follow up when he gets the issue sorted if he beats me to the fix :)

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Reset the timing to 24* per the '83 FSM; timing was rock solid at 2000, 3000, 4000 and 4500, didnt move around at all.

 

I did figure out the car has a ZX dizzy, but with Z31 internals including a Z31 CAS and Wheel.

 

Ive seen where people swap out the Z31 dizzy internals into a L28 dizzy when doing a Z31 ECU/MAF swap, but is the Z31 CAS and Wheel ok to use with the L28ET ECU/AFM setup?

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  • 1 month later...

This is most likely not the cause but worth a shot, I have a L28ET as well and was having real bad sputtering that progressed to the point where it would die. After looking all over I found that the gasket that is under the spring in the pop off valve had shifted enough to make it remain open all the time. This threw off the AFR so much the car ran horribly. Simply put it back in place and the car ran great.

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  • 2 weeks later...

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