fast951

Not knowing which setup you have, it'll be impossible for me to answer your question with accuracy. How odl is your setup?

We introduced the semi-batch in the early days, maybe 12-13 years ago? Hard to believe it has been so long, even harder to remember . How old is your setup?

It does not sound that the semi-batch is the issue. I would look at the Air Filter, back in the day we used a K&N filter. I have seen air filters create turbulence in front of the MAF causing erratic idle.

Try Rotating/clocking the MAF and see if it affects idle.

Is the ICV functioning correctly? How about the TPS? If either is erratic, the RPM will dip down.

Do you plan on running the fuel system as it appears in the picture? Way too many connections...

moalaska

I think system is pretty old, chip says 2004 on it, and it has the 55# injectors which you don't use anymore.

Tps confirmed working could be air filter issue it has beat up spectre filter on it and it. Ill simplify fuel connections.

Also sometimes when i shut it off let it sit for maybe 10 minutes and restart, at first afrs are a little high at idle but settle down shortly after. Could also be airflow turbulence through maf because of filter.

Tom M'Guinn

I applaud your tenacity, but think you are unnecessarily complicating things with that fuel system. LART sells 951 fuel rails and FPR/Dampers all on ebay at very reasonable set prices. You can't lose a bid with him, and he stands behind everything he sells. A rail/fpr/damper from LART would cost less than all those fittings, eliminate a huge unknown variable, and be a heck of a lot more serviceable/reliable/straight-forward. This seems like one of those situations where trying to save money and effort by fixing up a bad foundation is costing more effort and money in the long run, with no guarantees you can make it work. Rather than throwing good money after bad, I'd think you are better off cutting your losses and just doing it right with a 951 rail/damper and 3B bosch FPR. As for batch v semi-batch, if that were going to be an issue, you would see a consistent problem or pattern. That seems like an unlikely tangent to me. Fix the most obvious thing first -- the fuel rail/FPR/damper -- it's screaming to be fixed whether or not it's at the root of your problems. Don't mean to come across harsh, just trying to help...

fast951

Are you referring to the "2004" on the chipboard? It's the time we designed the chipboard. Nothing to do with your software.

AFRs a little high as in rich?

moalaska

lean. But its only briefly momentary and when at idle

fast951

Does it happen every time? How long is "briefly"?

moalaska

Ok today adjusted idle and made slight adjustment to fuel regulator. Now it idles good in the 14s drove it around quite a bit. If i shut it off and restart it shortly after, for maybe about 10 to 15 seconds afrs are about 15.5 but drop down to 14s after 10 to 15 seconds and consistently stay between 14.2 and 14.6.
This is at fqs position 0 fuel base pressure 43.5
idle about 900rpm

Things have vastly improved. I haven't driven it past 7psi of boost.

If I were to upgrade my system with your map sensor, is the fueling different because it can account for boost and airflow versus just going off of airflow through the meter?

Black51

Tom is exactly right.

You should NEVER see lean mixtures, period. You are simply over-complicating your fuel system. Even as close to solving your lean issue as you may be, it is still in your best interest in resolving the problem by putting a 951 fuel rail on. Among the myriads of 30+ year old failing parts on the 951, the stock fuel rail IMHO is one part still standing tall, in most cases.

fast951

You are moving in the right direction. With FP set at 3bar static, and idle at 850 +/-40rpm (900 is close enough). Your AFRs will dither in the 14s. So you seem to have nailed it.

As far as the lean for 10-15 sec, well without more data on hand and some data logging, it'll be very difficult to diagnose/guess from the description alone. It takes the O2 (std or Wideband) a bit to warm up. Is this what you are seeing?

The latest V-MAF+ software alters Fuel & Ignition based on boost. So both MAF (air flow) and Boost are taken into consideration. It'll be a good upgrade with many built-in features.
Keep in mind, if there is an underlying hardware problem, it must be addressed. The software upgrade is for performance and safety features and not to fix existing problems. Even the old software you have now, your AFRs should be very close to where you want to be.

moalaska

If it takes a short time for the o2 sensor to warm up that could be what im seeing. With it being 15 degrees outside im sure it cools off a little faster.

moalaska

Ok , so I hate it when someone starts a thread about a problem doesnt close it out and we are like"did you ever find the problem?" so I had a problem with my engine hesitating, running out of fuel, going lean, and then a lean misfire. What I tried

Rebuilt engine harness
New plugs
New wires
Checked fuel pressure
Checked all sensor functions in multiple locations multiple times
Multiple new engine sensors
New knock sensor
Swapped in extra set of injectors
Tried a second set of wires, oem new beru vs magnecor
switched back to old coil and cap
Checked injector harness with noid, and harness for continuity and shorts
Ran dedicated power/ground for maf
Resoldered dme, twice
Unplugged o2
pressure checked intake
Bypassed idle valve
Checked vacuum connections at wastegate
Found my original fuel rail and installed it with stock 3bar

Im probably forgetting some things, but pretty much checked about everything that could have caused issue. Swapped in a different dme and

Car runs great now!
Idle afrs are perfect, cruising afrs mid 13s set at fqs1, full boost mid 10s
Transitions into boost good, smooth powerband, no bucking.

I also found out that the bosch 3 bar puts out about 47psi static.

Just have to sort fuel issues with exhaust vibration and eventually do my waterpump, it drips about a teaspoon amount of fluid on floor after sitting for while, probably the gasket.

fast951

Good job, your hard work paid off. Glad you got it running the way it should.

raleighBahn

Nice!

And yes, the Bosch 3bar is more than that. I swapped to Lindsey's adjustable which is perfect. I won't even consider selling my old bosch 3 bar as I don't think they're the best choice due to that.

Alpine951

So your fix was to throw money at it and buy a used DME? I am in a similar situation. Car suddenly went lean at idle and boosting, bad idle. Done a bunch of testing, replaced sensor, parts, O2, noided the injector harness, etc... nothing. Been trying to find a DME some one could lend me to swap. Maybe will have to bit the bullet and buy a used working DME and hope it is the issue.

moalaska

there were things that did need addressing such as badly messed up harness connectors. And in process I know that everything is solid now electrically as far as I know. It was hard to diagnose as dme as problem was sometimes intermittent, then constant and symptoms looked like other causes.

if you haven't yet, try resoldering the dme first if you haven't yet.