Engine wont run right

Chrisfol82 · Post by **Chrisfol82** » Sun Jul 30, 2006 4:20 pm

MSII V3 Board, running spark through built in high current driver circuit. it is in a jeep 258 6 cylinder engine.

I cant seem to get my engine running again. I had it started about two weeks ago. I ran pretty good and i thought all i needed to do was get it tuned. Then like a day later when id start it up it would run really rough.

Then i went away for two weeks for work and now i can barely even get it started. It will crank over and sometimes try to catch. For a while i couldnt get it to run at all but now the best i can get it to do is run at about 400 RPM and it sounds liek its only running on a few cylinders.

Ive tried richening it, leaning it, advancing my spark, retarding my spark. I checked to make sure i was at top dead center on compression when my rotor is pointed at my #1 wire so i know im not liek 180 off or anything.

I pulled my fuel rail and i have fuel squirting out of all 6 injectors. I also know i ahve spark going to all my wires.

I cant figure out what is happening here. It ran great a few weeks ago now it will hardly run at all.

I pulled all my spark plugs and they are black but there isnt alot of buildup or anyhtign on them. They were a little wet though, but ive had them in and out about three times now. I checked one with it out to make sure it was sparking and it was.

Any suggestions would be greatly appreciated.

I was going to include my msq file and some logs but i cant see how to attach them here.

Bernard Fife · Post by **Bernard Fife** » Sun Jul 30, 2006 6:57 pm

Chrisfol82,

The most common cause of MegaSquirt ceasing to function after it had been working is excess residual flux. If you haven't already done so, thoroughly wash the main board in 99% isopropyl alcohol or acetone, and let it dry really well.

The second most common cause is cold solder joints. Use a hot soldering iron and touch up any that aren't perfect.

Lance.

Chrisfol82 · Post by **Chrisfol82** » Sun Jul 30, 2006 7:16 pm

Alright ill give it a good looking over tomarrow.

I ordered a new computer from DIYautotune after i had too many problems with mine. So i hope nothing too serious is actually wring with the board.

It started up and ran good at first. I hope a good cleaning will solve the problem cause im completely stumped as to what the problem could be otherwise.

Chrisfol82 · Post by **Chrisfol82** » Sun Jul 30, 2006 7:27 pm

Would that cause it run but just run really rough? or woudl that cause it to just not run at all?

Everythign seems to be working fine when i use the stim, and when i test it in the car, spinning a spare dist and with spare injectors hooked up everythign seems good, i get spark and i can hear my injectors clicking open. And it does fire just seems to be not on all 6 cylinders or not firing at the right time or something.

Anyways ill look over it tomarrow, the board might be sealed by DIYautotune, if it is im not sure how helpful cleaning it will be but ill still give it a try.

Chrisfol82 · Post by **Chrisfol82** » Mon Jul 31, 2006 3:18 pm

Well i cleaned it really good, checked it over for bad solder joints, i didnt find any that looked bad.

Tried it again and it does the exact same thing. It just cranks, seems to fire once or twice but wont get started at all.

Bernard Fife · Post by **Bernard Fife** » Mon Jul 31, 2006 3:33 pm

Chrisfol82,

I would try reloading the code. Then make a datalog and check it with MegaLogViewer to make sure you are getting a pulse width while cranking (you aren't in flood clear mode), you have power while cranking, you aren't resetting, etc.

Another possibility is that sediment in the fuel tank has been sucked into the pump and fuel filter. So you might have fuel squirting, but perhaps not the right amount - do you have a fuel pressure gauge?

Did you set the dwell when you installed megasquirt? What is it set at?

Check the coil as well - measure the DC resistance from the:
- negative primary terminal to the positive primarly terminal, should be 0.3 to 1.2 Ohms,
- secondary terminal to the coil's case, (~6K to ~10K Ohms)
- positive primary terminal to the case (should be infinite)

Are you injectors low impedance? If so, did you set the PWM parameters?

Have you checked the timing while cranking? It's always a good thing to check. And make sure nothig has crawled up the exhaust pipe and died too!

Lance.

Chrisfol82 · Post by **Chrisfol82** » Tue Aug 01, 2006 8:50 am

I have reloaded the code a few times, ill try it again tonight though.

My fuel pressure is right at about 50 PSI so i dont think its a problem with the fuel delivery, i get a pretty good stream out of each injector when i crank it over when i had my fuel rail out.

I have a few datalogs of it while cranking but i dont see how i attach them on here anymore.

I do get pulse width and i do get power while cranking. The engine will actually kinda run sometimes if i keep the gas in but it sounds like its only running on a few cylinders or somethin and it will only run at really low RPM's

I think i set my dwell to around 3.3 ill have to check to make sure when i get home. I think it says to use 3.5 for an HEI dist, so maybe ill put it up to 3.5 and try that. Although i doubt that would make much difference.

Ill check the coil as you described also when i get home.

I havent checked the timing while cranking lately i think i tried once before but i wasnt getting a good enough flash from the timing light to be able to really see what the timing was at.

Injectors Are high impedence, i never had to have any current control on them when i ran MSI.

Thanks for all your help so far, i really hope i can get this running again soon

Chrisfol82 · Post by **Chrisfol82** » Sat Aug 05, 2006 8:57 am

In checking the coil, what is the secondary terminal?

Is that the middle pin on the HEI cap that is between the primary pos and pri negative?

And this middle pin should be grounded right?

Chrisfol82 · Post by **Chrisfol82** » Sun Aug 06, 2006 12:40 pm

WEll i checked my coil. I get infinite between the positive terminal and the secondary ground. I get 1.1 ohms between the positive terminal and the negative terminal. So i assume there is nothign wrong with my coil.

It's still doing pretty much the same thing. Itll crank over and seem to fire once or twice. Sometimes it will act like it almost wants to run at about 300 RPM but sounds liek its only firing less than half of what it should be.

Everyhtign else witht he MS seems to be working fine. injectors are firing, both banks.

I dont know what else to try at this point. Unless theres a chance that the computer somehow went bad between when it was running and now when it wot get started right at all.