joejoe

I recently picked up another 928. '86.5 meteormetalic with 116k automatic. It has been on non-op since March due to not passing smog. It failed due to high NO(ppm) here are numbers:

NO (ppm) max 1106, ave 399, meas 2082 at 15mph (fail)
NO (ppm) max 936, ave 332, meas. 1494 at 25mph (fail)

CO(%) max .80, ave .13, meas. 0.00 at 15 mph
CO(%) max .60, ave .11, meas. 0.00 at 25 mph

HC (ppm) max 128, ave 41, meas. 55 at 15 mph
HC (ppm) max 103, ave 29, meas. 25 at 25mph

%O2 meas. 4.03 at 15 mph
%O2 meas. 3.61 at 25 mph

%CO2 11.90 at 15mph
%CO2 12.20 at 25mph

This test was on 3/7/12. I would like to get this one running on the road again and not part it out, but money is an issue at this time. What I have done so far (motor wise) is change timing belt, check cam gears (like new thank goodness), change coolant, change plugs, change air filter. The car had a poorly fitted K/N filter that allowed quite a few bugs into MAF.

Today I swapped the MAF from my other '86.5

Interior - pulled consol and replaced all vac diaphrams for hvac system 3 of the 4 were bad.

Of the paperwork I have the cat was replaced in '07.

The person I bought the car from has only run lowest octane gas, never tuned car, and really did not take very good care of it. When car failed in March the PO told me he took it directly to smog shop (maybe 1/4 mile) and ran it through, failing miserably. He did this because the owner before him told him it was the best way.

Is there anything else I need to look at before I take it in for a retest. I have run it about 100miles so far with 91octane and some bg44 fuel injector cleaner and plan on running at least 1 more tank of good gas before testing. (this test will be a pre test, if all good then real test)

As an aside the car runs like a raped ape, idles smooth and will always spin tires from 1st to 2nd under hard acceleration.

Hoping to get it going legally before sharktoberfest and bring all 3 down south. Any help is greatly appreciated.

Lizard928

You are too lean,

Adjust the CO on the MAF to richen mixture as per the manual.

dr bob

You are on the right track with trying to correct the lean mixture. Adjust the CO as Colin recommends, although the oxy sensor should be doing that for you already. Is manual adjustment an option on this US car with cats and oxy sensor? New oxy sensor can be added to your to-do list. You'll need to test CO ahead of the cats if you decide to adjust manually.

Cleaning the injectors usually takes more than a can-in-the-tank treatment. BG has an on-the-car force-feed cleaner that some dealers and repair stations use. Similar option from Snap-On and others. The full BG treatment package cleans the injectors by force, flushes oil out of the intake with a spray cleaner pushed downstream of the MAF, plus the in-tank stuff you already tried. All this stuff is on-the-car.

If your intake plumbing, fuel hoses and vacuum hoses are all original, treat yourself to an intake remove and refresh. You'll get to remove and clean everything above the engine valley. The injectors are sent off to your favorite cleaning place like Witchhunter to get de-junked, and all the tired leaky parts and hoses get renewed. Eliminating the vacuum leaks and a thorough injection cleaning should help bring the NOx numbers within reason. New fuel hoses will reduce the fire danger. You might find good already-cleaned injectors or a new set and take a week of waiting out of the schedule.

leperboy

The 85-86 US cars are adjustable at the MAF.

Although, without a sniffer or Blink'r it is difficult to know whether you have it dialed in. I think some have used a multimeter to read the O2 sensor voltage. A search here should result in the process and expected reading.

Matt

joejoe

I forgot to say I have changed the oxy sensor (one of the first things as well as releasing the pressure plate) I was hoping a known good MAF would help to get passed smog. The plugs I pulled were defenitly running on the lean side. Is it worth having a pre test with a known good MAF? Does the car need to be run to reset computer?

I must be in too much of a hurry as I cannot find the section to adjust CO in the wsm. (it is on other car now)

According to more paperwork in April 2003 a little over $5k was done on car. Majority of bill was timing belt and labor. Injectors 5 6 7 8 were replaced due to partial plug as well as gaskets seals intake boots a hose (92810744502) not sure which it is but think one from passenger valve cover as it is supple.

Thank you for replies.

fbarnhill

If you look up the instruction manual for the blinker I believe that you turn the 3mm allen screw on the top of the MAF CW for rich and CCW for lean. I will know more in the next few days as it is on my list to do. The blinker manual explains in detail how to do it with the tool but probably would be helpful for other methods also.

Lizard928

Doc,
85/86 cars don't truly self adjust. You need to set the CO via the pot on the MAF.

Shane

No computer reset on the S3s just plug and play.

Mrmerlin

https://rennlist.com/forums/928-foru...ight=maf+reset

Mike Frye

Really? They replaced HALF of the injectors?

That's like replacing one brake rotor or 4 spark plug wires.

Sounds like the car was 'reactively' serviced, which is always an indication you need to look for deferred maintenance. I'd replace all of them just because that kind of thing pisses me off and will always be an unknown until you do. Then work out the CO adjustment.

joejoe

Update--- car has passed smog.

NO(PPM) 15mph is now 174, and at 25 mph 330.

CO(%) .12, .14

HC(PPM) 90, 51

%02 2.6, 2.64

%C02 12.71, 12.78

For the test the original MAF was put back in after cleaning it. It had many bugs on both the top and inside of screens. I used CRC MAF cleaner on inside and it did clean the varnish fron sensor area. MAF was set at 380 off car and ended up at 598 after set CO was set using Kens' blink'r. Idle did come up a bit and is more stable at 800 (checked with infrared sensor off crank, not dash tach)

I was hoping with the paperwork showing a new address where enhanced test is not needed it would not need to do rolling test. I was wrong, but from this point forward it will only need static test from tail pipe.

While waiting for transfer I drove car a little over 120 miles with good grade fuel, and a can of 'guarateed to pass'. I think all it is is a fuel system/injector cleaner.

An observation I did have is after the adjustments and before the 'injector cleaner' the smell of the exhaust was much different. If nothing else it gave me the feeling that something had changed, and maybe for the better.

Left to do on car is cruise does not work, and driver door does not lock passenger side. When passenger side locked it will cycle but driver side does not move at all. This is for another post though if I cannot find a solution.

Thank you for all replies, and Mike that was almost my exact thought (I did have a few bad words thrown in)

James Bailey

In fairness to the P O they did ...." April 2003 a little over $5k was done on car." spend more on the car than it was worth !!

joejoe

Yes I guess that is right Jim. Unfortunatly the car had been through 3 owners since then (that I can find) and no other work seems to have been done. I really should not complain as I have many spare parts from other '86.5 and car was bought fairly cheap.