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

[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.

[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

[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]

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

[wazzu70]

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

[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.

[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.

[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?

[amcink]

Replace your Voltage regulator

[Dj Buttchug]

So does it start and die, or does it never even get running when using the starter?

itll start and die using the starter sometimes. Which leads me to believe I still have cranking setting problems.

It always bump starts, so i guess thats better than nothing at all haha. Ill get it sorted out. been kind of paying more attention to the e34 lately.

[wazzu70]

So does it start and die, or does it never even get running when using the starter?

[Dj Buttchug]

it goes as follows:

1st start from cold (bump start or cranking start) voltage is low (around 9v) until engine speed reaches 1300 rpm or so. For example, I bump start down a hill, engine starts up and reaches 800 to 900 rpm. I push the clutch in and put car in neutral. keep in mind I havent touched the throttle at all yet. At this point charging system voltage is 9 maybe 10 at best. All my dash lights are on and the car is running.

THEN,
I blip the throttle and instantly 14v is reached and engine settles back to idle speed. The voltage never drops below 14v after the initial blip of throttle regardless of engine speed.

cranking voltage is 9v always no matter what.

sorry for the confusion.

[LJ851]

... so it can be just sitting there idling at like 800 and im @ like 9 volts lol

Im around 9v DURING cranking which seems low. It only drops that low when the starter is loading the system.

Which one is it chuggz ?

[Dj Buttchug]

Truth, sounds like you found what to look into! Your voltage should not drop that low.

Is it 9V before you try and start it in the key on position, or does it drop that bad after engaging the starter?

Hopefully I get mine back up again this weekend so I can monitor the voltage during starting on mine.

Do you have a battery charger? Hook it up and then try and start it and see if that fixes it.

Im around 9v DURING cranking which seems low. In the key on engine off position im getting 12 consistent. It only drops that low when the starter is loading the system.
Ive been using jumper cables attached to a running car. It seems to start better when using these but its still not very good at all. The only way it actually works is when I bump start it.

[wazzu70]

So, when are you gonna get over this m42 insanity?

Why would he do that? :)