MicroSquirt.com read only forum (Jan.15,2018)

Afterwards however the ground strap that I have going from the back of my heads to the chassis was smoking f'ing hot!!!

Hope you fixed that ground strap.


It seems like you have plenty of pulse width but still might not be getting enough fuel.
Can you verify fuel pressure?
Sometimes the fuel pump gets wired wrong with the start key so that the fuel pump is only on during cranking.

Anyhow I see you got a burst to 1000 rpm. Thats something!

Jedrik wrote:

Afterwards however the ground strap that I have going from the back of my heads to the chassis was smoking f'ing hot!!!

Hope you fixed that ground strap.


It seems like you have plenty of pulse width but still might not be getting enough fuel.
Can you verify fuel pressure?
Sometimes the fuel pump gets wired wrong with the start key so that the fuel pump is only on during cranking.

Anyhow I see you got a burst to 1000 rpm. Thats something!

With the exception of not being able to tune...the car ran flawlessly before the swap. Although I have not checked the fuel pressure....I can only assume currently that it is alright. The fuel pump is still wired up to the stock computer...so I know it's correct. I've checked the power to the injectors to ensure they have juice with the key on and cranking...so there is no issue there.

I had some other runs that I didn't datalog where I was able to rev' close to 2k rpm with the accel enrichments on. I'm a bit paranoid about fouling the plugs again seeing as it's such a pain in the arce to change em.

As far as the ground strap goes…it gets smoking hot when the battery starts getting low and I start cranking it over a bit to much. I'm thinking it's not abnormal…and it cools off quite quickly.

I'm thinking that my next step is going to be to hook up the stock pwm iac valve back up to the stock computer and bumping the idle adjustment screw up a little bit more and go from there.

On second thought...I'm unsure if the stock computer will know what to do with the iac without the stock temp gauge being wired up. Hmmmm, any ideas?

The hot ground means you are getting a health voltage drop to the engine/starter. You probably know that. I wouldn't be surprised if your starter is not seeing 7-8 volts. Easy to fix and could cause problems in winter.

How does the old ECU determine that the engine is running?
Usually (as with MegaSquirt) the fuel pump is only toggled to prime the system and purg any air and then shuts off untill cranking is detected.

So it could be that the stock ecu is simply pressureizing the system and the elasticity of the hoses is alowing a drible of fuel as the pressure bleads off...
I would hook the fuel pump to Megasquirt. it is just one wire (to the stock relay) and would elliminate another variable.

Still, you say you are getting plug fouwling but at the same time it seems to be lean... curious

Jedrik wrote:The hot ground means you are getting a health voltage drop to the engine/starter. You probably know that. I wouldn't be surprised if your starter is not seeing 7-8 volts. Easy to fix and could cause problems in winter.

How does the old ECU determine that the engine is running?
Usually (as with MegaSquirt) the fuel pump is only toggled to prime the system and purg any air and then shuts off untill cranking is detected.

So it could be that the stock ecu is simply pressureizing the system and the elasticity of the hoses is alowing a drible of fuel as the pressure bleads off...
I would hook the fuel pump to Megasquirt. it is just one wire (to the stock relay) and would elliminate another variable.

Still, you say you are getting plug fouwling but at the same time it seems to be lean... curious

Yeah…I have the battery located in the trunk and grounded to the rear subframe. What I should do is probably run another wire from the ground out back up to the firewall where it's grounded to the engine. It's just one more thing on my long list of "things to do".

I suppose I could connect the megasquirt up to the fuel pump. I just have to now figure out exactly where to tie in. Damn my brain is swelling from the amount if crap I have to screw with when I get home!

Hey Jedrik...you da man!!!!

I had read about others using the stock computer to driver the fuel pump relay...but it appears to have been the root of the latter problem of not starting after the inital prime pulse. When I let the megasquirt control it...voila!!! It started right up and idled at 550 rpm . Needless to say I adjusted that up and still need to do some tweaking.

By the way...for all those interested, my relay was under the drivers seat and I spliced into the tan/light-green relay wire.

Great! Now the fun can begin.

If i had back all the hours I wasted trying to save time

Just got back in town from watching a taping of PINKS (the guys I sponsored lost the car, no fault of the MS) and I'm catching up on emails--glad to hear this is getting sorted out though. I didn't realize the MS didn't have control of the fuel pump, and the stock computer would see no reason to turn it on if it's not getting an RPM signal... so good work guys!