Resolved Bought a 1g after 15+ yrs

[NOMIEZVR4]

I bought a 1g DSM 93 AWD locally that seemed like a decent deal. I knew it had some issues, I've fixed some of the obvious stuff, now I'm trying to get the car running properly when going WOT. It feels like its got no timing advance under WOT, feels super lethargic. Even in 1st gear it falls on its face. Also it seems like the car despite having no timing was also hesitant to rev past 5000 rpms and that's with going partial throttle. I've done some basic maintenance and check ups and I'm looking for some insight.

Base timing is about 5-7 degrees
cam timing checks out all marks line up
fixed some boost leaks
New Knock sensor
Eprom ECU
emissions stuff seems to be deleted
2g MAS hardwired w/pigtail
FMIC and TBE
Tial knockoff BOV
Still 14b and 450's
running WG boost, I don't think I've seen more than 11psi

What I'm not sure about now is the EPROM. Is it possible that someone previously installed the 2g MAS without a proper chip and what I'm experiencing is the symptom of a 2g MAS on a 1g car with stock injectors? I haven't got any diagnostics on the car yet (loggers, etc)

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picture of the ECU

 

[NOMIEZVR4]

looking for options...here's what ive done so far.
-hotwired pump(assuming stock) i can hook up a fp gauge and do a pull and see what happens under WOT
-ngk bpr7es gapped to .26 w/new ngk wires
-checked for major boost leaks and sealed them
-verified cam and base timing at 5deg

possible to send my eprom chip to someone who can check whats exactly on it or just get a new chip burned also? really i need to be able to datalog and see whats going on

 

[1990TSIAWDTALON]

Bite the bullet and get ECMLink. Your life will be less complicated if you could. I usually say that it's the 1st mod to do right behind timing belt/balance shaft belt/water pump maintenance.

 

[pauleyman]

looking for options...here's what ive done so far.
-hotwired pump(assuming stock) i can hook up a fp gauge and do a pull and see what happens under WOT
-ngk bpr7es gapped to .26 w/new ngk wires
-checked for major boost leaks and sealed them
-verified cam and base timing at 5deg

possible to send my eprom chip to someone who can check whats exactly on it or just get a new chip burned also? really i need to be able to datalog and see whats going on

Please post a profile. Hiw are you running a 2g maf with no tuning solution?

 

[NOMIEZVR4]

Please post a profile. Hiw are you running a 2g maf with no tuning solution?

That's what I posted earlier, based on previous replies the eprom chip is not OEM. However I was suggesting maybe I should get a new chip or send this current one out to see if it's made to run a 2g mas on a 1g car.

 

[pauleyman]

With no knowledge of what it is I would suggest you scrap that chip. Go back to stock or go to ecmlink.

 

[NOMIEZVR4]

With no knowledge of what it is I would suggest you scrap that chip. Go back to stock or go to ecmlink.

Yep, that's the plan. Can't go back to stock cause I have no 1g maf and the pigtail has been modified

 

[92AWDHX40]

Ecmlink comes up for sale frequently I see on FB, a lot, great investment I remember using a gm maf, and a maf translator, even a palm pilot. Those were the days.

 

[NOMIEZVR4]

Ecmlink comes up for sale frequently I see on FB, a lot, great investment I remember using a gm maf, and a maf translator, even a palm pilot. Those were the days.

ill look on fb, didn't even think about buying there

 

[steve]

I've looked at most of the EPROM now and I'm not too surprised the car runs funny. It's looks like it was made by someone who had access to the DSM ECU archive while it was around but didn't quite understand what they were changing.

The chip has a simple stutterbox set up for 4500 RPM and a 7900 RPM redline. A shift light set to about 7500. They changed the boost gauge to display knocksum rather than boost.

They disabled fuelcut, disabled updating the octane index for interpolating between the timing and fuel maps. Made changes to both (fuel and timing), which I didn't investigate. I don't like mucking with the factory maps since this tends to be very car specific and falls into individual tuning rather than corrections for modifications. This is the primary benefit to DSMLink since the end user can easily make changes to tune vs. burning new ROM images.

The made some of the changes for a 2G MAF by changing the compensation table but forgot to change the multiplier and scalar.

Lastly they modified the chip to output half the airflow counts so a matching logger could show twice as much range.

 

[NOMIEZVR4]

I've looked at most of the EPROM now and I'm not too surprised the car runs funny. It's looks like it was made by someone who had access to the DSM ECU archive while it was around but didn't quite understand what they were changing.

The chip has a simple stutterbox set up for 4500 RPM and a 7900 RPM redline. A shift light set to about 7500. They changed the boost gauge to display knocksum rather than boost.

They disabled fuelcut, disabled updating the octane index for interpolating between the timing and fuel maps. Made changes to both (fuel and timing), which I didn't investigate. I don't like mucking with the factory maps since this tends to be very car specific and falls into individual tuning rather than corrections for modifications. This is the primary benefit to DSMLink since the end user can easily make changes to tune vs. burning new ROM images.

The made some of the changes for a 2G MAF by changing the compensation table but forgot to change the multiplier and scalar.

Lastly they modified the chip to output half the airflow counts so a matching logger could show twice as much range.

Thanks a whole lot for looking into this Steve, its such a blessing to have a DSM veteran local to me.

The 4500 studderbox does help to explain the difficulty the car has sometimes revving beyond that rpm range. How exactly is that supposed to work when its setup correctly? Because when cruising, especially on the hwy in 5th gear the car is very hesitant to loading up..its not happy at all if/when i give it gas to accelerate. The boost gauge setup for knocksum is known, yep.

I'm hoping the incomplete 2g maf settings combined with the other half-assed changes are all contributing together to how poorly the car is running. Mechanically its almost a near stock setup, it shouldn't take much for this thing to run like a good stock-ish DSM. So whats the plan from here? Do you want me to inbox you?

 

[CrackedDSM]

Didn't know you tapped the OG of OG's Steve to do the disassembly/read the chip. That sounds like hot garbage. I'm not a betting man, but right now I'd bet a decent chunk that is your problem. I really would also bet that even a 100% stock unmodified chip would fix the issues.


Steve you gonna burn him a new one?

 

[NOMIEZVR4]

Didn't know you tapped the OG of OG's Steve to do the disassembly/read the chip. That sounds like hot garbage. I'm not a betting man, but right now I'd bet a decent chunk that is your problem. I really would also bet that even a 100% stock unmodified chip would fix the issues.


Steve you gonna burn him a new one?

Yeah I hope so too. If he's unable to, them you know where I'll be going next

 

[steve]

The 4500 studderbox does help to explain the difficulty the car has sometimes revving beyond that rpm range. How exactly is that supposed to work when its setup correctly? Because when cruising, especially on the hwy in 5th gear the car is very hesitant to loading up..its not happy at all if/when i give it gas to accelerate.

The stutterbox code here looks at the VSS count to see if the car is moving, if it is the rev limiter is set to the higher RPM and if it isn't the rev limiter is set to the lower value.

So with this chip, sitting the engine should start sputtering at 4500 RPM and once the car is rolling it should rev to about 7900 RPM.

If the VSS in the gauge cluster doesn't work then 4500 RPM is all you'll get, ever.

 

[NOMIEZVR4]

The stutterbox code here looks at the VSS count to see if the car is moving, if it is the rev limiter is set to the higher RPM and if it isn't the rev limiter is set to the lower value.

So with this chip, sitting the engine should start sputtering at 4500 RPM and once the car is rolling it should rev to about 7900 RPM.

If the VSS in the gauge cluster doesn't work then 4500 RPM is all you'll get, ever.

got it. Yeah the speedometer does work, so then it rules that out.

 

[steve]

got it. Yeah the speedometer does work, so then it rules that out.

Two different things. The 1G VSS is a magnetic reed switch inside the speedometer gauge that pulls the signal from the ECU to ground. The speedometer itself can work fine and the VSS not.

The way to tell is either measure it to see if the signal is pulsing (at ECU, cruise control computer, or Diagnostic Connector) or see if the REV limit changes when the car is rolling.

 

[NOMIEZVR4]

Bit delayed but a worthy update. Decided to play the cheap route and get an eprom chip first instead of dropping 500+ for link. found one used that had a simple setup. I had some evo 560's lying around and it was setup for 2g mas/560's. Popped it in along with the injectors and it finally feels like a proper 14b 1g bolt-on DSM! It was great! Car is running 14psi in the video.

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Next steps now will be to make all the loose ends tight and make it into a proper clean-ish good representation of a 1gb DSM. Thanks everyone for your help! The plan for the foreseeable future as it relates to power goals will be simple...e16g, some variation of a walbro pump, and whatever it can safely push on pump 93. while all the other parts of the car get brought back up to spec.

 

[CrackedDSM]

Can’t beat simplicity! Love it.

 

[NOMIEZVR4]

Can’t beat simplicity! Love it.

agreed!

With that being said if anyone has a lead on a 16g variant...send it my way

 

[NOMIEZVR4]

So ive secured a deal with a local for a Precision SCM5031E. Eventually down the line it would be nice to crank this thing up to mid 20's on e85 to see what it can really do, but in the meantime, with 560's, 93 pump and a walbro pump how much boost is safely do-able? high teens?

Also without having to buy a pump twice, but also not overdoing it, should I toss in a walbro 450? that probably will require an afpr im assuming?

now that the car has deemed itself worthy, every project on it has been greenlit

 

[chrisman287]

Also without having to buy a pump twice, but also not overdoing it, should I toss in a walbro 450? that probably will require an afpr im assuming?

Anything over 190 will require an afpr

 

[NOMIEZVR4]

Ended up selling this car to a buddy of mine and he's been busy with it. Its local and ill be seeing it often, so im happy about that.

last we left off I did some maintenance on the car, new knock sensor, plugs, boost leak test, etc...my friend purchased some parts for it.

Walbro 450 pump
AFPR
Map/IAT sensor
DSMLink v3
old Precision SCM5031E
Precision 880's

Previous mods:
FMIC and TBE
Tial knockoff BOV
EVO 550's

car is running on v3 now, plan is to start installing the rest of parts and get it tuned locally. Any suggestions for a local tuner besides boostin? They are great but have a huge waiting list. wouldn't mind a remote tuner either. Car is pretty basic and he's not shooting for the moon

 

[lilbacha]

Not sure who all is still reading this, but here's an update BTW If anyone has any 272's I'm interested!:

Took a while to get the idle right and chasing one thing after another, Kevin @sixsigmatuning finished the Speed Density tune on pump at 21lbs.

New Parts Installed:
Rebuilt throttle body (Josh Bachman - Professionally done)
New short route FMIC core (previous one had poor welds)
Upgraded brakes to Carbon-ceramic pads/new rotors
New JNZ driveshaft bushings
New shifter base and cable bushings
Poly front and rear motor mounts
FP Exhaust manifold
PTE 1200cc Injectors

Threw on some EVO X wheels I had:

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and freshened up interior a bit (new seats and spray painted carpet black)

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Power mods to come:

ARP headstuds
272 Cams (looking for a good used set)
MORE BOOST (E85 Tune)

 

[NOMIEZVR4]

car is coming along nicely. Glad to see its heading in the right direction. seeing a mildly modified streetable 1g DSM in 2026 is a rare sight.

you should put a proper list together of all the items you have updated on the car since acquiring it.

 

[DreamChaser7]

Nice looking seats. What are they?