Imo000

Get a cheap single wire O2 and see if it makes a difference. Theya re around $30. get oen for a late 80's V8 Camaro.

BC

I may just have to do that Imo.

I received the known good MAF from a good friend in SoCal, and drove it around yesterday and to work today (about 20 miles).

WAY more power down low. It doesn't try and stall any more when you are taking off from a stop, and it can pull through 2-3k much better now. Obviously the car is running richer even with the 02 hooked up. I can smell the richness.

Before I took the other MAF off, I did do the CO analyzer for the tailpipe (look, no cats mom- **I had no idea**) - and it registered 0.0 or 0.1 %

I did not try and adjust the old maf before I removed it, but I doubt very much I could have gotten it up to 1% from there.

Drivability is much better, BUT - with the 02 hooked up, it still has a tendency to buck at part throttle or slightly accellerative part throttle below 3k and above 2k. When I REMOVE the 02 sensor, it does not seem to do it at all, or I can barely even feel when its doing it.



I have some questions for those that have dealt with the LH system more than I have:

1) What SHOULD the car feel like when you unplug the vac line from the EZK?

2) Does the LH system go to open loop in more situations than just WOT? Such as above a certain rpm?

Thank you

John Speake

1) If you disconnect the vac line the EZ-F will think you are at a high throttle opening all the time. To a first approximation this will mean less igntion advance. See Page 60 of the SharktunerLH2.2/EZ-F User manual http://www.jdsporsche.com/faqs/LH2.2...Issue%202b.pdf This shows advance vs intake vacuum via that hose to the EZ-F.

2) The LH will go open loop other than at WOT. ... when the MAF senses a sudden increase in air mass (to allow enrichment so no bucking) ......also at medium to high load values and mid to high rpm.

You should now adjust idle CO to 1% with your non-cat car as per WSM (O2 loop disabled) so you are judging the MAF properly.

It appears that your O2 loop wasn't working correctly before, as even with a badly aged MAF it should have been able to hold the idle mixture to 14:1 which is around 1% A/F.

BC

Thanks for your response again John.

Is there any chance at all that this is an early indication or failure mode of the LH? Above 4k, the engine runs very well, almost no matter what the MAF is.

I tested with the CO tester with the 02 disconnected per your instructions - should i have plugged the 02 in?

John Speake

The LH2.2 is usually very reliable much more than the later LH2.3 for MY87> I repair very few, and that is usually for gross misuse.

CO testing is done with O2 sensor unplugged, this defaults the O2 loop to the middle of its adjstment range. This is also of course where i will continue to be set when you did your test drive with O2 disconnected. I would suggest that a new O2 sensor would be good preventitive maintainance.

If you are clever with connections you would be able measure what the O2 loop is doing with the loop connected - the voltage should hunt around 0.2 to 0.7v. Old sensors can have a poor response time.

BC

Yes, I will be getting a new heated o2 sensor. The one in there looks like it was replaced recently, but in miles and not years. Years have passed since this car was driven alot. So its due.

Should the voltage really be down there? I thought low voltage was very lean?

BC

I'm posting from my phone in the car- no vac At EZF end of vac line

John Speake

Well, that's not right.....

AO

I thinks you have a vacuum leak somewhere (or terminated vac line).

BC

Its in the garage now. Gotta figure out where the vac is/is not before my drive to meetings 100 miles away in the morning.

BC

WE HAVE VAC!

Well, I do. Actually the EZF does.

Anyway, it was disconnected at the very stupid little 5 way connector under the MAF. I wonder how long that's been disconnected.

Thats not good that its that easy to lose signal to the EZF.

Now for the testdrive out of the garage to see if the hesitation/bucking is gone.

But first, chicken alfredo with artichokes for dinner.

neilh

Nice find Brendan, good luck on the drive tomorrow -
Neil

BC

Thanks neil.

BC

Just took it on my "performance loop" my my house. Its just nice when you find a problem, and can fix it, and then actually see a difference after you do. Just sometimes, its nice.

Holy Hell this car is going to be fun. Even with just the 2.2 rear end this thing is fast. Fast and torquey.

Every day gets better and that's always good.

I appreciate everyone's help very much.

BC

I wanted to return to this original thread to keep some semblance of continuation of theme. There are still some issues I would like to address here.

Known good MAF.

Replaced the Temp II sensor

Checked the air temp sensor, good ohms

Good vacuum at EZF vac port

ALL grounds that I can get to have been cleaned. No corrosion that could really cause any issues.

Coil wires randomly checked, all seem fine.

I have not replaced the 02 sensor.

..... The issue is below 3k. Its as if there is a switch. Below 3k the car runs as well as I could expect it to run, very good power, great throttle response, etc.

Below 3k is a completely different story. In high gears, it sometimes seems completely like a different car down there. Bad throttle response in higher gears, not as much reaction TO the throttle when depressed.

If you are in 3 or 4, and the car is warmed up, if you tip in, you can ALMOST feel a flat spot, and then it will wake up a bit, climb to 3k, and then take off. In fact, if I time it right, at part throttle, you can see the tach swing past 3k, and it will go from flat power to SZZZING! - past 3k almost as if a turbo kicked in. A very very small turbo, but a real, perceivable power difference.

I also can feel the WOT switch change the power level as well.

Any ideas?