Xvetteowner

My car is a 84 Euro, My plan was to tap into the wires on the plug. I understand its wire 6 and either 3 or 4. Would anyone know what colors they are? I am trying to avoid removing the MAF. P.S I got my mini vac and tested the Fuel damper and pressure regs, Both are holding vacuum. So My guess is the lean misfire between 1200 and 2000 rpms has something to do with either MAF adjustment or the need for a new one. Trying to adjust to get a reading of 1000 ohms. Which I understand is a CO of 1.5 Percent

John Speake

If the MAF is in calibration then 382 ohms is the correct starting point. If you need to go to 1000 ohms (max rich) then the MAF is well out of spec !

depami

Don't mean to hijack and I could probably find it with search but I'm lazy today:

Where in the US can one get a MAF tested / calibrated? LH & EZF too?

Edit: D'oh, sorry, it's right in Johns sig line. Not used to reading those.

neilh

Gary, the gunson tester you have ( I have also) is not that useful on a Euro. There is to much swirl ( ingress) of fresh air in from outside to make the probe accurate. On my daughters I could get the reading around 1.0, but when i plugged in the wide band O2 meter it never agreed, I went by the wideband reading. I installed a new cat, did everything i could to get the levels right to pass the CA test, and never did, so I shipped the car to my daughter in SC where they don't care

382 is your starting point, You can also check the resistance by pulling the LH connector at the ECU under the dash, and checking across pins 14 and 25.

joejoe

What is too high reading for maf? 900?

Xvetteowner

So since I thought my Gunson meter was correct ( That was a waste of $200) and I could not get a reading any higher then .09 I though using a ohm meter was my best bet, hence the question ( I did check search and scanned a few hundred questions) does anybody know what color wires I should connect to? Thank you in advance for any help.

John Speake

Anything over 600 ohms would suggest a MAF near end of life. This is because although you may be able to get the idle CO into spec, the effect of the pot is not linear across the output range.

So in the mid and upper load ranges you will still go weak with a MAF that needs lots more pot resistance to get the idle setting in spec.

A MAF that is 3% out of calibration will affect throttle response and power. I use that as my end of life figure. THat applies equaly to non cat and cat equipped cars.

Xvetteowner

Being I thought my CO meter was a good unit. Lord knews what kind of "adjustment" I set the MAP to. I am to need via search or another forum to get the color of the two wires that the ohm meter goes to.....its never easy

John Speake

It's easy enough to pull out the MAF and measure direct on the pins...

MY84 wiring diagram doesn't give wire colors. MY85 diagram gives 6 as Grey/red and 4 as brown.

Xvetteowner

John, What the heck was I thinking ( Corvette, Mustang, Etc) Removing the MAF was about as much a pain as removing a light bulb. From pin 4 to 6 I'm seeing 582 ohms. Since it seems to be leaning out what should I set it to? ( 84EuroS)

John Speake

:-) wasn't too bad, was it ?

If it's still lean at idle with 582 ohms then either the MAF is toast or there is an intake vac leak. Have you measured idle vacuum on the front fuel damper vac feed ? Should be around 21" at idle.

Xvetteowner

It was easy.... I'm even thinking on entering the 21st century and putting away my tach and dwell and the 50 or so Holley carb jets ( The under 35 year old guys are thinking What the hell is a carb jet?) I set it for 392 ohms and before putting it back I confirmed two full turns in equal a reading of 500 ohms. So if I need to go up scale I'll know what to do. At this point this 1000 to 2000 rpm miss fire is either the injectors or the MAF

John Speake

Yes, might be injectors... but often 1 or 2 which you here with car in neutral, slowly increase rpm and if it starts a slight shake as some rpm then it's likely to be an injector.

My moneys on the MAF - how many miles on the car ? If the MAf has been in there for > 80k miles then usually it is past end of life.

Xvetteowner

140k on the car, Motor is a Porsche replacment block. 4.7 or 5.0 not sure. Replacement blocks have no numbers. Does have the factory euro heads ( Car is the S model) Euro ECM, Euro twin dist and Euro intake, MAF was rebuilt by a Porsche/Mercedes/BMW shop in N.Y since the MAF is etched with there name, not sure when. So even with the MAF accepting an adjustment it still could be bad? The misfire, my guess is because of the injectors or the MAF. There are no vacuum leaks, idle rock solid ( and them some) no leaks at the fuel regs or damper, ( checked with mini vac) Dists set up correctly to TDC, number one plug etc, plugs new ( but wrong brand/type) wires check out with an ohm meter and no fireworks at night...but ( or at least before I adjusted the MAF to 395 ohms) a bucking between 1000 and 2200 rpms like I'm running out of fuel, If I give it more gas it will buck till around 3000 rpms then she jumps. My next step is to check the fuel pressure with a gauge. But 1st a test run when I get some free time to see if the MAF adjustment helped