megasquirt tuning issues

[59ragtop2276]

I have a 2275 with engle 120 cb heads... anyway i replaced the intake manifolds and after installing them I tuned it and it was runing great then out of no where it starting running bad the a/f was all over the place from what i could tell there is some sort of electric interferinance coming through the alternator it does have alot of slop in it but would that really cause the engine to run that bad now it wont even fire up it feels like it floods but when i go through the flood clear out ( you know gas to the floor ect) and it will kind of start but sounds like its only on 2-3 cylinders i checked to make sure the edis is hooked up and is correct and everything is where it should be and i made sure there is no vacuum leaks (soap and water) and no bubbles no change in idel so if anyone has any better understanding than i do maybe you may have a different route for me to take
thanks i really want to start driving my bug
RITA IS HER NAME

[fastfil]

Was this the first time its been up to operating temps with the EFI? Pull the plugs and be sure it is rich/flooding and not something else. Have you turned off the AE, ASE and WUE for initial tuning?

[Eaallred]

Soap and bubbles won't show a vacuum leak.
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Eric Allred

10.29 @ 131mph
Utah's fastest and quickest VW.

Aircooled.Net
Blackline Racing (Formerly ACE)

[the2ndcashboy]

[Dale M.]

To test for vacuum leaks, spray carb cleaner along any "joint" (gasket) areas and listen for change in pitch of engine... IF engine pitch changes you have found leak.... BE careful though carb cleaner is flammable....

IF you think alternator is causing noise in electrical system you may want to think about noise filter capacitor at input to POWER to EFI box and relay board....

Also lots of knowledge here....

http://www.shoptalkforums.com/viewforum.php?f=23&sid=307702b2c4bf5932821031da6bfe2adf

Dale
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Lives his life vicariously through his own self...
1970 "Kellison Sand Piper Roadster" For Street & Show.

All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ...

[miniman82]

What ignition system?
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Build thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=212747

[MinamiKotaro]

If you aren't using resistor plugs, switch to those and see if it makes a difference. You can pick them up at the auto store when you go to get some carb cleaner to check for vacuum leaks. They're inexpensive.
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1967 VW Beetle
2276cc
MegaSquirt-extra v3.57
Check out my ongoing story.

[Boolean]

Use water to check for vacuum leaks. Engine will stumble when you find a leak.

[59ragtop2276]

No it has been running on and off for awhile now got it up and going awhile ago after finding the map sensor was bad and replaced that by the pros not me tuned it and it ran great then found a crack on the intake manifold took 3 months to get the parts got them installed got it tuned ran great then all of a sudden just started running bad if i remember correctly the iac was sending off a strange signal when I was looking at it while tuning it but i made sure the connection was on I dont want to replace it without making sure that might have been it I was trying to lead on to that area but no one picked up to it so maybe I no onw else has experanced these same problems and yes it does have resistor type plugs and the only thing i can think of when it comes to a vacuum leak is from the intake where they bolt up but that whould have showed right off the batt and i will pull the plugs and see if one or more are fowled oh last question about what should the fuel pressure be at idel thanks

[59ragtop2276]

yes i know it will stumble with the water just one of the little things they teach in automotive school (wyo tech) the other guy i guess just is one of the people that like to watch bugs drive down the road with scorch marks licking up the decklid and back window (non sealed flamable liquids in a hot area) its the fumes that light not liquid arosol flamables not to smart

[Dale M.]

NEVER had carb clean ignite while looking for vacuum leaks.....

NO I do not like scorch marks on deck lids...

Your fuel pressure at idle should be same as at high rpm....

Any WYO Tech grad who paid attention to his instructors should know that....

What fuel pressure are you setup for something around 40psi?... What ever the pressure regulator is set for it should not vary across the whole rpm range (unless you have turbo)....

Dale
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Lives his life vicariously through his own self...
1970 "Kellison Sand Piper Roadster" For Street & Show.

All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ...

[skills@eurocarsplus]

[miniman82]

OP- where in the San Joaquin valley are you? I used to live in Lemoore, plenty of VW folk there that can help. I also know watercooled VW guys who are familiar with EFI, if the location helps. If you're close to Lemoore, hook up with the aircoolers.

http://autos.groups.yahoo.com/group/LemooreAircool...amp;slk=34
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Build thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=212747

[Dale M.]

[mcmscott]

[59ragtop2276]

Thanks for the infomation from some people that may have abetter understanding of this system. I will try to call them asap but wont be able to get the car worked on for a few days because of the rain and the fact that my garage is full up with parts and stuff. I think im going to try to replace the alternator first to see if that makes the interferance go away if not i guess the sensor is bad or not insolated correctly so that will be next after that i guess I will just work my way down the line (what i was trying to avoid) but without any type of obd system it just takes more time to narrow down the issue but hopefully one of the tuners listed above can point me in the right direction so thanks again for all the info ill keep everything posted as i move along hopefully i will be able to make it to the Sac bug-o-rama in Rita (and to the guy who said something about my schooling i built my first frame off restore by the time i was 14 from a 63 euro bug then by 18 built my first show a 63type 1 rag full custom with recaro seats with embrodered vw emblems on the head rests and the quarter panels shaped in a vw emblem, berg shifter, porsche matillic silver polished 5 spoke empis, prostreet tranny and a killer 2056 with fk-98 with heavely welded heads, adjustable beam, sway-a-way rear torsion bars and adjustable swing plates just for a light idea on what she had done to her, there was more to her but you get the drift) so to answer your remarke i did get my knowledge from the real world but to be a mechnic of any kind you have to get your ASE cert which takes schooling im not saying that i know everything or i wouldnt need help with this efi system but i have been around the block so to say when it comes to any car and just to make sure your mind is at ease i did all the work myself except lay on the paint on both cars. Oh and just for a little more knowlegde about me i used to help out with cory mac's top fuel car you know the "big boys" but there is still nothing like a flat 4 running in the high 6's so once again thank you to the people who are trying to help me and for all the people who doubt me ill see you at the sac show ill be lined up with Rita ready to run and drive her back home oh and to answer the question on where i live in stockton off 8 mile closer to lodi than stockton thou. Sorry for rambling on it just bugs me when people have know clue on what i know and talk down to me like they know the right way todo everything cause if you think you know it all you really dont know much but thank you very much to the people who are truely trying to help out a fellow vw fanattic and remember keep your vw's on the road to quote Gene Berg (the only thing that can totally kill your vw is rust, the rest is easliy fix able) so drive them as much as possible

[fastfil]

Your fuel pressure should be as low you can run it and still maintain a good spray pattern. It'll depend on your injectors, some need more pressure than others. As said, around 40psi at idle is usual - unless you're maxing out their duty cycle. In which case you'd up it a bit (if your lines can take it).

Your fuel pressure regulator should then raise the pressure as manifold pressure rises. At idle you're injecting into a partial vacuum (maybe 40kpa). At WOT you're injection into atmospheric pressure (100kpa ish). By raising fuel pressure with MAP your maintaining the pressure differential between the fuel supply and where it is being injected to. This maintains the relationship between injector pulse width and actual volume of fuel delivered preventing your fuel maps from looking skewed. It also give the injectors greater range.