Smelly Exhaust -TurboZ Hybrid

[cygnusx1]

What are common causes for the 280ZXT motor to run rich? Mine seems rich as the new tailpipe turned black inside very quickly. When I come to a stop the "vapor trail" smells awfull. It is running great otherwise but it seems to run too cold. It usually runs between 140-160 degrees-F. Could that make it really rich? It has a new oxygen sensor and new injectors. The ECCS system is wired correctly AFAIK I checked it over and over comparing it to the Nissan prints. All the injectors are ticking OK and fuel pressure is to spec. I could pull a fast one and add some boost but thats not the right solution.

 

VEHICLE:Bone stock 83 Turbo Motor and ECCS with 2.5" SS Exhaust and DP. in a 76Z.

 

Dave

[Jersey]

Hey Dave. What harness did you use - your 76 or the 83? What's your timing set at? Is the green LED on the ECCS flashing after holding steady on the pedal for a bit @ 2k rpm? If it running cold, the Head Temp sensor is adjusting fuel pulse for this temp and could very well be the cause of your richness.

[Guest Nic-Rebel450CA]

running rich could also be the cause of running cold..

 

how are your spark plugs. if your plugs quickly fouled then you may not be able to find the cause until fresh plugs are put in. also, your coil may be firing very weak and thus not delivering enough spark.

 

more info :

has your car been sitting for a while?

did this happen all of a sudden like one morning BAMM?

[cygnusx1]

Background info: It is a recently finished 83ZXT motor into my 76Z with the entire 83ZXT ECCS system transplanted. Timing is 24 BTDC.

 

Today I discovered that the thermostat was stuck open so I put in a good one that I tested in hot water. It is a 180 deg one. The car seems to run much less rich everywhere except downhill deceleration where I can hear pops in the exhaust that may indicate still a bit rich on decel? I set the TPS idle contacts very close so that it come off the idle contacts VERY quickly after touching the gas pedal....maybe it is too close and I need to back it off a bit. I will try this tomorrow. Also, turning the idle-air-mixture screw on the AFM at idle, seems to make NO difference in idle smoothness, speed, or smell. In my N/A motor, this screw actually used to make a noticable difference in idle smoothness when turning it from in to out. Driving at low RPM and very light throttle causes the motor to "buck-bump-miss" just a tiny bit. I suspect this may be also related to the TPS contacts.

 

Don't get me wrong, it is running 99% perfect I just want to iron out these little quirks.

 

Thanks for the input.

Dave C.

 

EDIT: BTW: should the green LED flash or not and what does it mean either way?

[Guest Nic-Rebel450CA]

Timing is 24 BTDC.

Woah, do these engines really run that far BTDC?! Or is that a turbo thing?

I can hear pops in the exhaust that may indicate still a bit rich on decel?

Yup, that's rich. I'd try backing off that TPS and I would be concerned that the AFM screw doesnt make a difference.

[lifegrddude]

I don't know if 82's and 83's are different as far as timing goes, but I'm pretty sure my 82 runs at 20 BTDC. I'll look at my hood again for the emission's info and see what it reads b/c I've never touched my timing.

John 82ZXT

[SleeperZ]

I don't know if 82's and 83's are different as far as timing goes' date=' but I'm pretty sure my 82 runs at 20 BTDC. I'll look at my hood again for the emission's info and see what it reads b/c I've never touched my timing.

John 82ZXT[/quote']

 

They are. The '83 ECCS specifies 24 BTDC, all the others are 20 BTDC. Keep in mind this is just the timing for idle (the ECU uses this point for the reference for all timing), so the TPS should be closed when setting the timing. The engines are of course the same.

[cygnusx1]

Just a note....I am still running rich on decel and idle. I also noticed some weird stuff regarding my ECU green LED so I started a new thread.

 

http://www.hybridz.org/phpBB2/viewtopic.php?t=26103

[Guest bastaad525]

The car will run rich if it stays in the 'cold' mode... car should be at a normal running temp of 180. A badly adjusted AFM can cause rich running at idle and cruise. My car's running a little rich in that area too... I kinda had the same thought "Hey a good excuse to turn up the boost" problem is that a mis adjusted AFM would only make you run rich up until 4000 rpm or so, at which point it is opened to it's maximum amount... so even though it may be running rich up to that point, it could very well be quite the opposite at high rpms under boost... so not a good idea If you check/change everything else, the next best thing to do is get to a dyno or a cooperative smog place and adjust the AFM with the car running under load to get the best idle and cruise mixture.

[fl327]

ive yet to see a turbo transplant that doesnt run a little rich.

24btdc is indeed for 83 only, but it can be adjusted +- 3 degrees from factory spec, and a tad more when tuning for max performance.

sidenote: my buddy ran 18btdc with 83efi and a flattop f54 shave p90 turbo engine with 8.9 cr, hybrid turbo and 10psi as a daily driver and didnt ping.

Im not sure what the difference is with the settings, ive run 81-82 ecus on my car at 24btdc and it ran the same as my 83 ecu, with the slightest difference at idle only???

 

I set tps really tight, the milisecond it moves, its open, or is that closed?

I made a transparent shield for it so I can see what its doing.

[cygnusx1]

I wonder why they run rich after transplants??? It must be the ground loop quality because nothing else has changed except for the fuel tank, and lines. Hmm, maybe we should run a big steel braid loop and tie all the FI points, motor, battery and chassis to it. It ounds like it may be worth a try - nothing to lose except for cost of braid wire. Over in the Subaru WRX forum, people swear by the difference of running big ground braids everywhere to smooth out the FI system performance.

 

When I did the swap, I was extremely careful with the grounds. I dremel polished all the contact points on the motor, body, and harness to make them clean and shiny. I then used a bit of silicone grease and stainless steel bolts to be extra sure. My AFM is undisturbed and is still factory sealed. I am not saying that it is fine but it has not been abused. I wish I had a way of quantifying the "richness". Right now I go by smell, idle smoothness, and exhaust pop.

 

I want to test the head temp sensor and the O2 sensor. What readings should I get at what condition? I cant find an FSM anywhere.

 

I was getting 0.3-0.5 volts at the O2 sensor last I checked at idle fully warmed up to 180 degrees.

[Guest bastaad525]

Haynes manual has all the procedures and numbers to look for when testing sensors also. AFM's can go out of adjustment over time even if they've never been opened before... they are spring loaded... I guess after a while the springs can loosen up, hence the flap moves a little easier/further, hence the car will run more rich. The AFM is really one of the only things you can tinker with to adjust mixture on these cars w/o having to buy something, like an adjustable FPR. I too made a big deal out of grounding everything and I know my grounds are clean and good, but the car still runs kinda funky. They ARE very important from what everyone says here but I dont think I've had one person here ever post that simply cleaning up or relocating their ground connections to better spots ever solved any problem....

[cygnusx1]

In my NA Z, I played around with the gearwheel in the AFM to change the mixtures within the AFM useable range. However, there really is only one spot on the wheel that gives a nice smooth idle so I left it there. I never had the luxury of an exhaust sniffer to get it perfect - heck there is NO emmision control testing in my town anyhow! I will give it a whirl with the Turbo Motor.

[zguy95135]

the exhaust smells bad when the cat converter goes bad too.

 

what does it smell like?

[Guest bastaad525]

I'm thinking of reinstalling a cat... I know it wont help my performance but I'd rather keep my lungs in good working order

[cygnusx1]

Smells like a Z; rich with hydrocarbons. It don't smell like a stinky catalytic converter (sulfur/rotten eggs) because there is no cat.

 

Maybe a cat would help. Has anyone cured the stinky, eye irritating, open window driving, cabin exhaust smell in a Z with a catalytic converter?

 

Good thinking dudes!

[Guest bastaad525]

yeah there is definately no mistaken fart stink cat smell for kill you quickly hydrocarbon smell

 

By the way, for what it's worth, I've only ever had that sulfur stink smell on so called performance or 'free flow' cats. I cant say I ever recall smelling the slightest nastiness from a good ol' regular, performance robbing stock replacement cat. It really becomes a hard decision... what is more important, those extra horses and/or less turbo lag? Or my health. Anyways I found out why my car has been just killer on the smell lately. The gasket that goes between the turbo and downpipe sprung a massive leak. Gonna fix that tommorow. Before swapping the turbo motor in, when I had my N/A, the exhaust smell was almost non existant, this was with no cat, after I had replaced my rear hatch and tail light seals. I suspect after changing the gasket tommorow, the smell will once again be pretty much gone.

[cygnusx1]

I changed all the rear end body/lights gaskets and even sealed the vinyl under-hatch panel that lets fumes in through the hatch latch. With the windows shut I get no smell in the cabin. The exhaust comes in only when the windows are open while driving stop and go. Putting the ventilation fan to "4" helps a bit.