L28et running/idle issues

[jhill]

So I will preface by saying, 1978 280z, rebuilt 1982 F54 with a new datsun parts llc p90a head, o.g. ECCS efi, new-ish stock injectors, turbonetics t3/t4 new motorsport auto AFM, new walbro 255 fuel pump, new BEGI rrfpr. The engine is missing a few things, cold start valve, carbon canistor, and the VAC has all the ports plugged. The engine runs O.K. but I have a few issues.

 

1. Idle- It idles at nothing but 1k rpms which is too high. Try to set it any lower and it jumps all over the place and wants to die. At 1k it sits right at vac on my boost/vac gauge and sounds pretty nice. I thought these cars idled at like 600-700? Also I'm not sure if running the car with the VAC could be contributing to this?

 

2. Timing- Its off the chart advanced. When I rev the engine with the light on it the mark comes just about to the most advanced mark on the chart and then dives back to the abyss. I have double checked the timing marks on the crank and chain and they are perfect. I'm thinking maybe the distributer or CAS is bad?

 

3. WOT- Now this varys just about everytime I put the throttle down. Sometimes, It will pull hard all the way to my 5500 rev limiter with a miniscule amount of black smoke trailing me. Other times it will throw fuel out the tailpipe like a diesel dummy pickup truck. And then lastly, most of the time it pulls hard and then falls flat about 4k rpms. It will still build rpms as long as I keep the throttle down but usually I let off because it feels like its starving for fuel and my narrowband (need a wideband) gauge falls all the way off to the lean side.

 

 

Im worried that the tank is rusty, but could that be causing all the running issues?

 

 

Thanks for input, The car has about 1000 miles since the rebuild and its really time to sort out the bugs. I'd like to go megasquirt or haltech but that sits on the back-burner until the money says otherwise. Until then I'd like this ECCS to run the car better considering all the new parts.

 

 

*I forgot to mention the car has a violent backfire issue when decelerating in gear. I did some reading on that and mostly found everyone saying its okay just run it that way but when I decelerate for 5+ seconds at 1500 or more rpms I get what sounds like somebody shooting a .44 handgun out of my exhaust.*

 

*Also when I press on the throttle very slightly while driving around, I dont get a consistent amount of power. Its very minimal, and if I'm not paying attention its barely even noticeable but it will deliver power then hesitate then power then hesitate.*

Edited April 3, 2012 by jhill

[Gollum]

Is the AFM new to this setup?

 

What's your ignition setup? ('81 CAS on the pully, '82-'83 Dizzy, other dizzy, etc)

 

What's your coil arrangement? (stock coil, msd coil, stock coil + helper box, etc)

 

Was the engine running fine before the rebuild? If so, what's changed since then?

 

Any other known electrical issues?

Edited April 2, 2012 by Gollum

[NewZed]

1978 280z,

rebuilt 1982 F54 with a new datsun parts llc p90a head,

o.g. ECCS efi,

new-ish stock injectors,

turbonetics t3/t4

new motorsport auto AFM,

new BEGI rrfpr.

 

1. Idle- It idles at nothing but 1k rpms which is too high. Try to set it any lower and it jumps all over the place and wants to die.

 

2. Timing- Its off the chart advanced. When I rev the engine with the light on it the mark comes just about to the most advanced mark on the chart and then dives back to the abyss.

 

 

3. my narrowband (need a wideband) gauge falls all the way off to the lean side.

Until then I'd like this ECCS to run the car better considering all the new parts.

 

Mainly interested 'cause this looks like something I might do. Edited your post for focus.

 

ECCS - is it for a turbo or NA? In the FSM, ECCS and EFI are too different computer systems. You said ECCS efi...

RRFPR - is this to take the place of the turbo ECCS? You're running an NA ECCS with a RRFPR? If you have a turbo ECCS why do you need a RRFPR? Are you running NA injectors with a turbo ECCS and an RRFPR?

AFM - turbo or NA? For the 1982 ECCS?

Injectors - turbo or NA?

Narrowband sensor - that's how they work, you're either rich or lean.

Timing - the "abyss" is retarded or highly advanced? It starts advanced and retards with revs or vice versa? It starts "off the chart" and comes visible? Not really clear. Real numbers are good also, e.g. sits at 20 degrees then goes to 40...

 

Just trying to figure out what you have and what's going on. Some of my questions might be obvious (for example the ECCS might be turbo only in 1982). Looks interesting.

Edited April 2, 2012 by NewZed

[jhill]

*I forgot to mention the car has a violent backfire issue when decelerating in gear. I did some reading on that and mostly found everyone saying its okay just run it that way but when I decelerate for 5+ seconds at 1500 or more rpms I get what sounds like somebody shooting a .44 handgun out of my exhaust.*

 

*Also when I press on the throttle very slightly while driving around, I dont get a consistent amount of power. Its very minimal, and if I'm not paying attention its barely even noticeable but it will deliver power then hesitate then power then hesitate.*

 

Gollum-

Yes the afm is new to this setup, its also a completely new unit from motorsport auto.

 

Its got the CAS on the distributer and I believe its an 82 distributer.

 

Its a brand new stock coil.

 

Yes, the engine ran pretty solid before the rebuild, always pulled hard right to redline. It never had any of these running issues.

 

 

Newzed-

Its the ECCS for the turbo motor, sorry for the confusion.

 

The rrfpr is hooked up for when I want a couple more psi of boost, but right now its adjusted to add no extra fuel. The injectors are newish stock turbo injectors.

 

The afm is a new turbo afm for the turbo ECCS

 

The timing is super advanced. The timing mark at idle is so far advanced its down below where you can see it, thats what I meant by abyss. I wish I could give you some real numbers but its not visible until I rev the engine, at which point the timing mark will just start to appear but not actually move up to the 'timing reference chart'. Also if I try to bring the rpms up and hold them at any point the mark will be so far advanced it wont be visible.

[Gollum]

Where's the dizzy in it's range of adjustment? Should be fairly close to middle.

 

Have you tried the 'ol disconnecting the ECU trick? Seems like you're either having an electrical issue or one of the sensors is way out of spec.

 

I know the AFM is new from MSA, but it might still be worth it to pull it out and check it against the FSM test method to at least see if it's in the ballpark and to make sure it doesn't have any dead spots in the traces.

 

 

I know this can be hard to do when a lot has been changes between setups, but think through EVERYTHING that's been changed since it was last in good running shape. The problem lies somewhere in something that's been done. I've seen plenty of L motors that sat for 5+ years and fired up fine. Yes cleaning electrical connectors is always a good idea and should be done at least every 20 years, even in sunny california, but if it was running fine before then it's more likely than a connector isn't seating right because of being messed with, not because of corrosion.

 

It might also be worth it to check ALL your sensor readings at the ECU pins per FSM procedure. That will tell you if you've got connectivity or grounding issues for each sensor.

[NewZed]

So it's basically a stock 1982 turbo motor setup. I looked around but can't figure out what a VAC is. Is that the right acronym?

 

With the stock ECCS, isn't static timing set advanced, like 20 degrees, and the ECCS adjusts it when running? Sounds like your ECCS isn't doing its job or is getting the wrong signals. The FSM says that "timing can go wrong if the crank angle sensor mounting position gets out of alignment. When this happens the crank angle sensor must be adjusted". Also odd is that your timing would retard with revving. I thought that would only happen under boost.

 

The backfiring is probably due to incorrect AAC and VCM operation also, if I read the FSM diagram right.

 

One more thing - are you feeding the ECCS and the AFR meter from the same O2 sensor? I don't think that's allowed. I think that a bad O2 sensor can cause a rich mixture also.

 

Anyway, the FSM is full of diagrams and descriptions addressing idle control specifically (there's about 12 things involved just in idle control) along with all of the other devices. Good luck.

[Challenger]

A couple things to check. Throw on a gauge to see what your pressure ACTUALLY is. If you think the tank might be rusty the return line might be clogged, that would make your fuel pressure higher at times possibly. (just happenned to me)

 

Also as far as your idle, I dont know what all youve plugged on your manifold but make sure you didnt delete the idle controls. If so, just adjust the idle screw.

[cgsheen]

1. Idle- It idles at nothing but 1k rpms which is too high. Try to set it any lower and it jumps all over the place and wants to die. At 1k it sits right at vac on my boost/vac gauge and sounds pretty nice. I thought these cars idled at like 600-700?

 

 

The stock L28ET will idle at ~1000RPM if you've disabled or removed the AAC. Without the AAC operating it's running slightly rich. The ECU applies vacuum to the AAC (through the VCM, which is just a couple of vacuum solenoid valves that control vacuum to the AAC and the EGR valves) at idle to admit a little more "bypass" air which balances the AFR and should pull your RPM down to ~750.

 

There is no idle speed ajustment or adjustment screw on the stock L28ET. The ECU controls idle speed. The ECU controls spark advance and initial timing at idle should be ~20 degrees BTDC. As stated above, that's normally about center of the adjustment range of the distributor...

Edited April 3, 2012 by cgsheen

[Gollum]

The stock L28ET will idle at ~1000RPM if you've disabled or removed the AAC. Without the AAC operating it's running slightly rich. The ECU applies vacuum to the AAC (through the VCM, which is just a couple of vacuum solenoid valves that control vacuum to the AAC and the EGR valves) at idle to admit a little more "bypass" air which balances the AFR and should pull your RPM down to ~750.

 

There is no idle speed ajustment or adjustment screw on the stock L28ET. The ECU controls idle speed. The ECU controls spark advance.

 

Umm.... wrong...

 

There's an idle adjustment screw on the throttle body. Just a little screw that acts as the throttle stop point. If you removed this screw so that you had "no idle adjustment" the engine would die. The tricky part is that indeed the turbo AFM has no idle bypass and thus also has no idle mixture screw. So yes, it will be a bit rich at 750rpm, but it WILL idle there. Once the O2 is warm it will actually idle off of O2 and magically run a bit smoother. I daily drove my L28ET for quite a while with NOTHING but my boost gauge and brake booster running on my intake manifold. EVERYTHING else was plugged off. On cold mornings I'd have to brake with three feet to keep it from dying if I just drove off in the first 30 seconds after startup, but after getting about a mile down the road it'd idle just fine down around 500-600rpm, then once it was warm it'd idle closer to 800rpm.

 

There's no reason for a L28ET with the AAC removed to HAVE to idle at 1000 and run piss-poor bellow that.