The 15 Y/O Turbo M42 Build Thread (Now Holley EFI Terminator X Controlled)

[amcink]

Replace your Voltage regulator

[wazzu70]

Wouldn't the voltage regulator allow too much voltage if its bad?

Ryan, what req_fuel are you using when you have the starting issues? What is your ASE total time?

[Dj Buttchug]

Wouldn't the voltage regulator allow too much voltage if its bad?

Ryan, what req_fuel are you using when you have the starting issues? What is your ASE total time?

its not the voltage regulator. The alternator and regulator are brand new.

req fuel is @ 6 currently. Ill have to check on my ASE time real quick so ill report back. I moved all my tunes back to my PC so I could better organize things.

[LJ851]

its not the voltage regulator. The alternator and regulator are brand new.

The symptom you describe is usually a bad alternator or the wrong size pulley on it.

[wazzu70]

I was wondering if there were multiple pulley sizes available. If there is, thats one thing I would definitely check.

[Dj Buttchug]

interesting idea guys. i have an extra m42 alternator. Ill compare it to my new one and see.

[Schnitzer318is]

Yep another detail I should point out is that I dont see 14 volts until I raise the engine speed to say 11-1300 by stepping on the gas. The battery light is on until the revs are up so it can be just sitting there idling at like 800 and im @ like 9 volts lol

At least you get to 14 volts. I never see that much voltage. lol. I run in the low 13's most of the time.

My cranking is in the low 12's - low 11's if I remember correctly (depending on how long since last start).

[Dj Buttchug]

At least you get to 14 volts. I never see that much voltage. lol. I run in the low 13's most of the time.

My cranking is in the low 12's - low 11's if I remember correctly (depending on how long since last start).

yea but at least yours starts up haha.

heres where im at tho. So it was mentioned that I may have the wrong size alternator pulley and this got me thinking. I couldnt recall having this bad of a start up issue when I moved away for school and brought my car. I remember driving it around a few times before i completely wasted the clutch.

One thing led to another and I ended up robbing my turbo car for parts (alternator) when my other m42 powered sedan left me stranded. I swapped two things. 1 crank sensor from turbo car to daily and 2 alternator (I later replaced with a brand new OEM bosch unit.

After I replaced the alternator I always had excessive amount of belt slack. my tensioner was always maxed out and the belt was still not as tight as id liked it to be.

So what if my new alternator (thats still currently in the car has the wrong size pulley) Not even thinking about this I went down to the parts store, bought a size smaller vbelt and popped it on to solve the loose belt issue.

So it comes down to cranking voltage. Does the alternator generate voltage while cranking.... enough to make a difference....

I still have yet to compare sizes with another m42 alternator. Been busy with the e34 lately. This subject made me feel the need to spill all my thoughts on the matter

[wazzu70]

The alternator wont do anything under cranking. The alternators purpose is to recharge the battery from the power used to start the car and the power used to run the electronics.

It is interesting your car runs at 9v though after being started. Thats not normal.

Try the shorter belt. On my car if I remember correctly the alternator is as far out as you can get to keep the belt taught!

You can also take the alternator off and have it tested at the local parts store.

[LJ851]

Sounds like you could be on to the reason you have low voltage after you crank.


They voltage while cranking is determined by battery condition, wiring/connection condition, and starter condition.

Once it fires the alternator has to reach a certain rpm to "turn on" and start charging. This is usually designed to be below idle speed so that it will charge instantly but it sounds like you may be spinning the alternator slower than it should be.

9V while cranking is low enough (too low) to cause issues with a fuel injection system. Some systems are more sensitive than others but once you reach the voltage level that is too low for your setup it will be very difficult to start and will run poorly.

You may have multiple issues going on at the same time.

[Dj Buttchug]

So i forgot to update my current status. Below is the culprit of all my headaches. Thank you guys for trying to help me out. I got so fed up with this start up issue I had to go back to basics.

5 minutes on a scope and BOOOM. Issue resolved!!!!


This crank sensor IS NOT OEM. I bought it off line and the little phucker cost like 80 bucks.... Come to find out its dropping signal during start up and randomly sending sparatic low signals. It also had a reputation to send signals with insane amounts of noise... it looked like aliens were taking over my oscilloscope. I got so tied up in thinking the cranking settings were off that I let it get the best of me.

lesson learned.
Put OEM sensor in and now it starts every time with less than 2 seconds of cranking. Smooth idle too, just a chit load better all around.

Now I can FINALLY move on.

Also 92s look ok i guess... gonna run em for a while. Gloss brilliant white PC. needs better pics, ill get some soon

[wazzu70]

Awesome you solved the problem! That blows it was just a cps all along! VR sensors in general are very prone to noise/error which is why newer sustems use hall sensors.

Those 92s look pretty nice. 15"? What offset? A classic wheel!

[Dj Buttchug]

Awesome you solved the problem! That blows it was just a cps all along! VR sensors in general are very prone to noise/error which is why newer sustems use hall sensors.

Those 92s look pretty nice. 15"? What offset? A classic wheel!

dude ya. Finally figuring it out just puts me in a great mood. lol

Specs are 15x8 et20 205/50/15 Nitto Neo Gens

[LJ851]

Boom!

Good job. I feel like there should be a sticky somewhere about non OE/OEM crank sensors. No one should be running one !

[TheTacoMan]

Jolly good, literally pages of trouble shooting for a shit sensor.