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Timing issue around 4,000


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#1 Ipjkcu

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Posted 05 March 2018 - 11:17 AM

OK quick run down. 89 stock rebuild bottom end. Mildly worked head. Possible aftermarket cam 25/65 rpm range.  5spd. 2.5 down pipe no cat. 3in gm maf / maf t v2.  50/68 t3 turbo. 15psi some creep on 3/4 gear pulls Afr are good all across board. Idles afr 13-13.5 cruise 14.5-15 mid 13-12 wot 12.2-11.5

It's teasing me some times at 4 to 4500 rpm in first or second the thing just moves. Braking traction as expected if not dry.. But most often it just kinda stays flat boost is there afr stays steady. Pretty sure it's timing related. But maybe I need to get a new coil I switch it and seemed to be a little more consistent in first and second but 3rd and 4th flat.
I have a nodded Mazda tps. Set correctly. But max v with throttle all the way open is 4.15 4.22? changed out Ics as noise switch was not working.  Could the problem be the gm maf in higher rpm range. Anyone ever experienced that? And vac advance is working and in good standing alone with cap rotor and wires new plus. 36 gap.
May disconnect knock sensor. And retime and see if it's knock related. No bs.

Just looking for thoughts and ideas. Could be wiring harness issues as I have had more then one wire break from connectors. I fix and repair as I find them but have not dug deeper into harness. As shortly the motor is coming out and into an 86. And Fiji will see life with different motor and trans.

So to those g54b guys. What's the last thing you would think of that is most likely simple and the problem 😁





#2 croquest87

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Posted 05 March 2018 - 11:23 AM

Mine did that  it turned out to be vacum advance

Edited by croquest87, 05 March 2018 - 11:41 AM.


#3 Ipjkcu

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Posted 05 March 2018 - 11:37 AM

I switch it out. Easy enough. I have a few dizzy and a couple of vac units laying around see if it changes anything..

I suppose I. Need to look into more details on how these dizzy and advances actually work.

#4 croquest87

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Posted 05 March 2018 - 11:42 AM

Ordered brand new one through advance auto last summer was around $30 bucks so l don't have to guess my old once

#5 Ipjkcu

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Posted 05 March 2018 - 01:31 PM

Is there any difference between 89 and 86 dizzy and vac advance? Could be I have the 86 installed?

#6 croquest87

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Posted 05 March 2018 - 02:15 PM

I would get the 87-89 new one   some 86 or other years may be diferent  you need a turbo one for sure

#7 scott87star

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Posted 05 March 2018 - 02:42 PM

I've locked out advances on dozens of dizzys for ECU setups and I've found most of them don't have a functional centrifugal advance, the grease has turned to glue so the poor thing can't advance if you spun it to 20,000 rpm.  I've had to pry the last couple off when it should slide easily.  It only takes 20 minutes to strip a dizzy, clean all that old grease out of there and relube it so you know that part works and you can test both the vacuum advance and boost retard function while you're at it.
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#8 Ipjkcu

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Posted 05 March 2018 - 05:30 PM

I was thinking it could be that but what don't. Make sense is that at times it pulls hard in first and second but not in 3rd. Am sure it lies somewhere between dizzy and vac advance.
Be nice to find the limits of the stock fuel system. Haha

#9 croquest87

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Posted 05 March 2018 - 05:34 PM

Yea all that 30 year old stuff should be taken apart and greased/replaced

#10 Ipjkcu

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Posted 05 March 2018 - 06:49 PM

Just poking around during breaks at work took cap off. Vac advance works as should.. holds pressure. Everything seems to slide like it should.  I will tear down one I have in shed and get new cap / rotor and coil

#11 Ipjkcu

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Posted 15 March 2018 - 01:50 PM

Replaced coil, cap, plugs, dizzy is good all slides. Had some lose bolts on turbo adapter as well runs much better, builds boost quick but just kind poops out around 5,000 rpm @15psi afr is good. Maybe too much for stock IC piping or maybe tps only seeing 4.2

#12 croquest87

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Posted 16 March 2018 - 03:46 PM

Secondary injector dirty but clean enough to a certain point? Just a guess
15 psi + will kill that engine quick if you lean out real good couple of times lol  its just to much for stock pistons and all  yes it will do 15+ psi  question is for how long?

Edited by croquest87, 16 March 2018 - 03:48 PM.


#13 Ipjkcu

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Posted 17 March 2018 - 11:28 AM

I have no issues with it leaning out or running rich, I've cleaned the injectors visually the spray and flow look good and this problem is not just on this throttle body/injectors as I have switched them out.  And yes the engine won't last long when running lean. As long as bearing clearances are at spec, and put together properly, in use with head studs and quality head gasket.  And regular oil changes. Such dirty engines haha.  Running high boost and leaning any turbo engine will cause engine failure quickly.
Over the years there are a hand full of people who have properly built and maintain there g54b engines, the engines have there issues. But from carb to turbo versions I have never been afraid of being broke down. They are and can be very dependable and reliable. But when in search of more power its the chances we take. I have spare blocks and heads, it's time and money. It's the chase and challenges I enjoy.  In the next few weeks I will be pulling the 54 out of 89 Fiji and change tb to put in 86 have a crazy idea of running no maf running afc neo of map and maybe a small roots supercharger along with turbo., of course I will need better IC and bigger piping, also problem widen factor exhaust port and make bigger. Of course those are just thoughts and ideas at the moment. The hear will be transplanted and guts will be removed from Fiji to get new life with 6spd getrag and 1jzgte vvti.

#14 Hoosierquest

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Posted 17 March 2018 - 12:24 PM

I'm wondering if your cam timing may be a little off. You mention an aftermarket cam, and if the block was decked etc that can also change timing. Unfortunately the only way to check it is putting a degree wheel on it.
If you had an adjustable cam gear you could retard it a few degrees and see what happens.
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#15 Ipjkcu

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Posted 17 March 2018 - 01:52 PM

It's a possibility, but not likely. I have had issues with keeping turbo bolts on and have actually ran better 0-60 times with it leaking causing lag in lower rpm but building steady power from 3 to 6. I know most people might say sound like you need a bigger turbo. But I think it has to do with air flow really. I have not pushed stock fuel limits past there point and I know it's capable of better numbers.
But I am a noob really and read a lot, trying to filter the bs from fact. Just when you talk about power and the 54 there is not much info unless mpi. The tbi Most of it has washed away over the years. It's something that people didn't spend a lot of time with as it was new then old real quick. Haha I wonder what type of numbers one could get switching intakes and running a blow through carb set up. As people have perfected blow through carb set up and mpi. Now where in the world of direct injection. One day maybe  I will sway in a 3.5 ecoboost haha. I do need to check and adjust valve train could be a slight problem but the turbo leak and power in high rpms. Hmm maybe I will stop over at a friend's he's got a bigger turbo laying around. Haha.  The wiring is cracking in 89 fuji all over the place my modded Mazda tps only sees 4.2 at most. Not the 4.5 the ECU sees for wot. I have tested 2 different tps same results on and off,  can anyone verify that the Mazda tps produces 4.5 on or off the throttle body. If so maybe a new tps as the ones I got where junk yards




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