Dea_944t

Did my first start-up and logging with a Vitesse Stealth V-Flex kit (MAF, #83s, MAP, Piggy-back, Zeitronix logger).

Since the car hasn't passed the annual vehicle inspection I can only drive it in the parking lot which means that it's a bit hard to tune it to prepare for the inspection.

After letting the car idle for app. 5 min I logged the following (car standing still):

Idle (~900rpm): AFR was moving around a bit but generally around 15-16, vacuum 350 mmHg/14inHg

2500 rpm: Steady AFR at 14.6 - 14.8, vacuum 470 mmHg/19mmHg

The 2500rpm values indicates that the lambda sensor is OK and the vacuum values that there are no leaks.

Any ideas on why it's slightly lean at idle? ( I would have guessed on slightly rich since it wasn't warm yet)

At the inspection only CO and HC are measured at idle, not lambda, so I will probably pass anyway unless the slightly lean condition causes high HC?

/Dea

fast951

Assuming there are no vacuum leaks and your are running the correct fuel pressure and the FQS is set correctly!
More than likely you are experiencing a minor voltage drop between MAF sensor and DME. The drop is caused by the solder connections and wiring.. At idle the signal is around half a volt, so any drop will be pronounced and it'll run a bit leaner.
Nothing to worry about, just compensate for the voltage drop (at idle or globally) by enriching the appropriate cells and you'll be fine.

Dea_944t

I don't think there are any vacuum leaks as the values at idle and 2500 rpm looks OK and fuel pressure and FQS settings are OK.

I thought the closed loop would compensate and get to 14.7 also at idle?

I'll enrich a little to get thru the inspection and then check again when I can get better logs.

/Dea

Dea_944t

I think my car is trying to tell me: "- keep your dirty hands off my engine".
Went to the garage this weekend to slightly enrich the idle and try to find out why I have smoke coming from the header/wastegate area to be able to pass smog inspection.

Started the car and let it idle and after 15min the smoke finally stopped so something was probably burning off.

Checked the AFR at idle and it was around 16 but when holding it at 2500rpm it didn't stabilize at 14.7 anymore, instead it dropped to 12.....??

Any ideas?

/Dea

fast951

The simplest way is to undo whatever you did to enrich idle, see if the 2500RPM changes.. If it does, then the way you richened idle needs to be done differently.

If it doesn't make a difference, it's time to start chasing ground issues or heat related issues.

Since your kit was used when you got it. Did you clean the MAF sensor before installing it?

Dea_944t

I didn't change anything in the PB, started with checking that everything was working (which it wasn't).

I didn't clean the MAF but I checked it and it did look clean. What's the proposed cleaning method?

I'll go over all groundings asap. Not sure what heat related problems there could be?

/Dea

Paulyy

usually theres this special spray you just spray on the sensor and cleans it, it's like air. i forgot what it's called though

Dea_944t

Did some more testing today and there seems to be multiple problems...

- Checked the MAF and it looked clean
- Checked for vacuum leaks but I don't think there are any
- Checked the cabling and all connections again and they are all OK, will test to move the chassis ground for the pins on the PB that needs this next time

Cold start with PB.
- Idle AFR around 16 after 1 min
- 2500 rpm AFR steady 14.7 (this one is a bit uncertain will double check the logs)

Varm running with PB
- Idle AFR 15.5-16, rpm ~850
- 2500 rpm AFR, first 14.7 for 2 sec then dropping to 12

Warm running without PB
- Idle AFR 14.7, rpm ~950
- 2500 rpm AFR, quickly passes 14.7 and then down to 12

Tested to disconnect the original lambda sensor which made idle worse in all warm running cases and made no difference at 2500 rpm.

When double checking all PB parameters I noticed that the "Fuel lower limit" is at 0.0 instead of 0.3, and although I changed it and download the new map it stayed 0.0V when uploading the map? All other changes are accepted by the PB and stays in memory.
Not sure if this could affect idle?

Some conclusions?

- The PB lowers rpm and makes it run slightly lean and unstable at idle so it seems to be changing the signals a bit, not sure why as everything is set to "zero" in the maps

- Either the original lambda sensor or the wideband isn't showing correct values at 2500 rpm or the closed loop is somehow disabled?

Next test will be to log also the original lambda sensor voltage to see if it matches the wideband AFR
Other than that I'm out of ideas....

/Dea

JohnKoaWood

Which (if any) regional coding plug is installed in the DME harness near the DME? it is a 2 pin plug , near the DME, and controls fuel / timing behavior as well as open / closed loop behaviour..

http://motronic.ws/4in1.htm

There are 2 different plugs (shorting or 1.4Kohm) as well as no plug installed...

Your location is listed as Sweden, but Sweden market cars were delivered without NB Lambda sensors.... but you have one.... I.E. if you have the ROW market coding plug installed, your DME is ignoring the Lambda sensor!

Tom M'Guinn

It depends on which Vitesse product he has. The coding plug typically invokes race gas maps with the Vitesse chipboard, and that can either retain or eliminate the closed loop system, depending on how the chipboard is programmed.

Tom M'Guinn

Have you set the base idle yet, using the instruction in clarks-garage?

What do you mean when you say "without PB" -- are you using the shorting plug?

Have you confirmed your TPS and DME temp sensors are working correctly?

How sure are you that you have no vacuum leaks? Many a 944 owner has sworn he has no leaks, only to later discover them.

What's the history -- did you just install all these parts and now you're trying to get them to work -- or were they working and now something's changed?

The 0 v .3vdc would not cause these issues.

Is your 2500 rpm test sitting in the driveway with no load -- or while driving up a hill?

Dea_944t

Thanks for the ideas!

There is no plug installed and according to the Vitesse manual this plug is used for pump/race gas choice.
From 88-89 all Swedish cars have cats and NB sensors My car originates from Germany but that shouldn't make any difference.

Haven't set base idle but it's perfect without the PB.

All tests with PB is with the shorting plug connected.
The 2500 rpm issue is the same w/so PB.

TPS seems ok, I'm logging it, but I will check that the switch in it works as supposed. Haven't checked the temp sensor.

I've disconnected all hoses and checked for cracks and I would expect a leak to cause a lean condition?

The system was bought used and installed this winter. No issues with any of this prior to installation.

All test are in the driveway.

Will do more testing tonight.

/Dea

Dea_944t

Did some more tests tonight where I had the NB lambda sensor connected to PB and Zeitronix for logging:

No PB, warm idle
- WB shows 14.7
- The NB signal goes from 0.15 to app 0.7 V den down to zero again etc. not a nice sinus curve but it seems to be in closed loop at least

No PB, cold at 2500 rpm
- WB shows 14.7
- The NB signal goes from 0.15 to app 0.7 V den down to zero again etc. not a nice sinus curve but it seems to be in closed loop at least

No PB, warm at 2500 rpm
- WB shows 14.7
- NB steady signal just over 0.8V no changes so it's not in closed loop


PB, warm idle
- WB shows 15.5-16
- NB steady at 0.12V no changes no not in closed loop

PB, 2500 rpm
- WB shows 12
- NB steady signal just over 0.8V no changes so it's not in closed loop


I had a strange behaviour at the end with no PB, warm idle where the NB was steady at 0.22-0.3V and the WB showed 14.7 - 15.2 so no closed loop.

So the NB sensor seems to be working but closed looop behaviour is strange. With the PB connected is never goes into closed loop and withit disconnected it does in idle, most of the times, but not at 2500 rpm.

Still no clue to why the PB doesn't hold the "fuel lower limit" in memory. It didn't seen to log the NB correctly either....


/Dea

Dea_944t

Any last ideas before I dump the car in the ocean? (or go back to AFM..... ).

I've given up on the PB but it would be really nice to get it working with the MAF, MAP and chip.

Did some more checking/testing today with only MAF, MAP and chip

- Cleaned MAF, no difference
- Checked TPS at DME connector, OK
- Checked the MAF connections at DME connector, OK
- I have earlier logged the MAP and compared it to the Zeitronix boost sensor and a mechanical boost gauge and they all match

Started the car and logged and there is a clear connection to engine temperature. At cold the AFR at idle and 2500rpm is 14.7 and the log from the narrowband sensor shows that closed-loop is active.
When it gets warm two things happen:

- idle increases from app 850rpm to 950rpm
- closed loop only works at idle

Measured the DME temp sensor and temp gauge sensors and both showed OK values compared to spec.

So something (a temp sensor of some sort) seems to be affected by temperature or there is a problem in the program as soon as it gets out of the cold start phase.

The kit was originally to a -86 USA/Canadian car and mine is a -90 Euro but to my understanding this shouldn't matter.

I really hope I can drive it soon, the engine feels more responsive with the MAF-kit.

Next on the the test list is to change map on the chip board and log MAF voltage.

Any other ideas?



/Dea

Tom M'Guinn

How did you wire in the NB signal into the piggyback? How did you pick up the NB signal?

There are a handful of things that can knock the car out of closed loop.

A bad o2 harness can cause it. Confirm that DME pin 24 has continuity to the harness side O2 plug under the hood when the car is warm. Wiggle the wires when testing to check for bad connections in the harness.

The car will not be in closed loop when the full load signal is triggered by the KLR. To test, run the motor so that it should be in closed loop but is failing to stay at 14.7. When the motor is running like that, check for 5 volts on pin 18 of the KLR. If it instead shows 0 volts, then your "full load" signal is on, which could be either a bad KLR, or the throttle position sensor is giving a bad reading (i.e., it is indicating a wide open throttle when the throttle is only slightly open).

A TPS that falsely shows an open throttle can cause it. To test, KLR Pins 22 and 23 should have 320-670 ohms with the throttle closed and 2.7k-4.7k with the throttle open, when a smooth progression as the throttle opens.

If AFR is too far out of range, the o2 cannot pull it back to 14.7. Might test the temp sensor at the DME (to check both the sensor and the harness). Confirm DME pin 13 has 1.4k-3.6k at ambient temp and 160-210 ohms at 100c.

If you have a spare DME handy, try it.

Confirm that the regional coding plug is not installed, as this could put you into race gase maps which may or may not use the close loop system.

Confirm that you have zero exhaust leaks in front of or near the o2 sensor, as those can (and will) throw off your readings and cause you to chase your tail.