Failed Emissions 85 735i with Motronic 1.3 Upgrade

[pennybond]

Hi all!

Just got back from an emissions test and these were the results.



85 735i with Motronic 1.3 upgrade. Also have valve cover vent going to catch can and then to air filter box (not to the intake boot.) Newer cap, rotor, wires and plugs. I did change the oil last week with Castrol conventional 20/50. The O2 sensor was replaced 2 years ago but has only about 10,000 miles or so on it. When I replaced the O2 it did make sure it was dithering correctly between about .80 to .25 volts. Also HVAC system leaks but I have the vac line going from the intake plenum directly to the heater valve so I can control cabin temperature. This pod does not leak.

Is there anything inherent in the 179 ecu that would be overfueling the B34 or should I be looking at how the AFM is set? Arg!

Thanks for any direction!

[kojo96]

I know someone with a euro 10:1 motor running motronic 1.3 and he passes CA smog! Running rich? Try and check AF readings.

[pennybond]

One thing I forgot to mention is I have this in place of the stock 179 chip:

https://www.ebay.com/itm/RACE-Chiptu...ppVJ:rk:1:pf:0

[Hit Man X]

HC is unburned fuel. Go from there.

CSV could be leaking. Injector bleeding down. FPR bad. Is the cam to distributor cap seal leaking oil? BTDT on the 300SEL when it was smogged. You should pull about 17" of vac at idle. How old is the oil? Was the car hot? 80*C thermostat?

[pennybond]

Kojo & Hitman, thanks for the replies. I'll take a look at how the O2 sensor is behaving. Oil is new last week. I removed the fuel line from the CSV when I did the 1.3 upgrade and left the CSV in as a "block off plate." I'll have to check under the dizzy cap for oil. FPR should be good as I'm getting just under 40 psi at idle. Injectors should be good. They are remanned Bosch 19# Mustang (Orange body.). The engine runs smoothly and pulls well, no hesitation or flat spots. Temp could be suspect as the car normally runs with the cluster temp gauge not quite to the straight up & down position. (Toward the left.) This happened before however it ran even cooler. Turned out to be a pebble propping the thermostat open so it couldn't fully close. That was strange!

[pennybond]

Ok. Here is a little more data...I hooked up my multimeter to the O2 sensor and it seems to dither around .7 to .4 volts at idle. If I introduce a vac leak, (I removed the vac line to the FPR) the dithering drops and moves around .1 to .3 volts. Reattach the FPR vac line and the reading jumps to 1.1 and settles back into the .7 to .5 volt range.

Next I wanted to check the battery voltage and I found something strange....the voltage while the engine was running was 11.82. When the engine is turned off the voltage reading moves back up to 12.15. Now a few years ago I did your voltage regulator fix, Mr. Hitman, and I thought I should be seeing about 14.5 V??!! Really strange. I removed it and inspected the VR thinking it may be an issue with the solder joint or the diode itself but all seems to measure out. There is a drop of .655 volts on the diode which I compared to a brand new one I had and it measured .654. The Bosch voltage regulator is stamped with 14V. Any ideas why that may be happening? Could it affect spark intensity and lead to unburnt fuel? I know when I did the regulator fix a few years back I was getting 14.5 V.

I still need to check vacuum but all I have is a MightyVac. Can that be used to measure? I think the 17" reading you quoted is some kind of mercury gauge?

Thanks!

[pennybond]

I just looked at my MityVac...The gauge is in in. Hg vac! Just tested and it was 17" on the nose.

One more data point to add...my gas mileage has been terrible 13 to 15 mpg with a mix of city and highway. I thought my odo was not measuring correctly and I tested it over several months and it was off (under reporting miles) by about 7-8%. I attibuted that to my wheel/tire (225/50/16's) combo it could not explain all of the divergence in mpg.

[pennybond]

Ok I know its late...but I was now tracking down the the voltage issue stated above. The battery light was not coming on upon turning on the ignition. I removed the cluster and checked the battery light bulb and I'm getting continuity so the bulb is good. I put everything back and turned the key again and the battery light lit up....I started the car and checked voltage across the battery terminals and I'm getting 14.5V as I should. (Don't ask me!) So this is not the issue. Enough for tonight, back at it tomorrow.

[Hit Man X]

Maybe the voltage regulator is turning flaky. What all was running when you saw 11.82V?

My 013 ECUs act weird with low voltage. I would assume the 179 does also.

13-15mpg is pretty poor for mixed. I did 15mpg, city only, with my Euro 8:1 735i, five speed. You should easily match that with batch fire EFI I would think, if not improve upon it. I seem to recall about 20-22mpg freeway, 65-70mph.

[pennybond]

There was nothing running except the engine and radio, maybe my seat heater. Seems to be working ok now. My voltage regulator is only 3 or so years old......and this car is not driven very much. Maybe I was having this low voltage issue during the emissions test.

Could the cheap ass Ebay performance chip I have a link to above be causing the overfueling? I wouldn't think so for idle and just expect it higher in the revs. Do my emissions numbers above looks like it is extremely rich, or just a little? How about the O2 voltage numbers I posted above. I think they are saying that it is running on the richer side (dithering between .7 to .5) but it does not seem too bad? I know what the standards here are but they are different than other states so I'm not sure what baseline on our cars should be.

[Hit Man X]

I have seen them in the thousands above limit. I think you are pretty close. Was the catalyst hot?

[pennybond]

The cat may not have been hot. It took me about 15-20 minutes to get to the test station. About 5 minutes freeway and 12 minutes at 40 mph on a larger roadway normal revs. Probably should drive around more before I have it tested? I noticed that the second test run was lower and that was after the tester reved the engine for a minute at 2500 rpm.

[Hit Man X]

I am not the best with these questions, most of my crap is exempt. I can tell you, towards the end, higher mile engines and cats are just not very efficient at lower engine speeds. I would drive around at 3-4k to heat that shit up. Then swing into my inspection stop, have it put on smog machine instantly.



...like what plugs are best for a 1.3 on an 8:1? Silvers still or something else? I know the kat needs to be hot hot.

I would look for a used exhaust gas analyzer, most stuff on road is OBD2 so rarely uses a sniffer in my area.

Chip could mess it up, unsure. I only have used the Dinan (junk) and EAT (MUCH better) in an 059.

[pennybond]

Eric, I appreciate all the ideas. I wish they would not be so stringent here on these old cars. Mine is approaching 300k with original cat. I do run silvers and I have a ton of fresh ones I can throw in. I also just ran some Seafoam through the FPR vac line and I'll run a little water through later hopefully to get rid of any carbon buildup.
Thanks again,. I'll keep at it!

[Hit Man X]

The cat on my 300SEL was super lazy once it got past about 250k or so. 325k now on it, but somehow the cat was gutted. Weirdest thing ever..

[motohunter4]

Are you exempt next year?

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[Jay535is]

I have a 10:1 with 1.3 wtih stock M50 cats (yes M50) and it passes smog without issue.
Step 1: remove that junk ebay chip and put the stock 179 chip back in.
Step 2: drive it for a week or 2 to let the ECU find new nominal values and get back to baseline.
Step 3: return air intake to stock spec (remove catch can) and make sure AFM is at stock position (no extra or less clicks)
Step 4: Drive the car at higher than normal revs to the Smog station, get tested

With just HC being over its not your cat, you have an overfuel issue. Most likely culprit is some janky ebay chip.

[pennybond]

Motohunter....mine will never be exempt here in Oregon. All gas powered cars built 1975 or later have to have a emissions test!

- - - Updated - - -

Hi Jay,

Yes I am planning on swapping the chip back. I kept the stock chip but I can't find it now....I've ordered another 179 ecu and it should be here in a few days. Never hurts to have a spare when they are cheap now.

[pennybond]

Ok, so after some help from you guys above and the following:

Seafoam treatment through intake.
Water treatment through intake.
New NGK spark plugs gapped at .30 (ZGR5A).
New O2 sensor.
Removed catch can vent hose from air filter box.

Even though I have not received the stock 179 ECU I decided to go get tested again to see where things are. I drove there at 3.5 to 4K rpm to get the cat nice and hot. (I did have to sit and idle for about 10 minutes before it was my turn unfortunately.) Here are the results:

First Idle Standard Observed Pass/Fail
HC 220 244 Fail
CO 1 0 .9617 Pass

Second Idle Standard Observed Pass/Fail
HC 220 256 Fail
CO 1 0 .979 Pass

Moving in the right direction....just a bit further to go. I have a question....If the system was running in open loop would these be the type of figures that would be observed? I ask because I have modified the O2 wiring to use the Bosch #15718 (i think for Ford) because it is $25.00 instead of $75.00 for the Bosch "BMW" long wire. (Who wants to pay $50.00 for extra wiring???) Anyway I had to take an old long wire sensor and splice in a Ford connector to be able to plug into this sensor. If the sensor signal wire (Black wire) has a bad/intermittent connection could it cause these above results? I'm going to check continuity on the O2 wiring tonight when I get home.

Thanks!

- - - Updated - - -



In case the above is unclear.

[motohunter4]

I'm with Jay on the eBay chip. Go back to stock. Your fuel map is off.

Sent from my LGLS755 using Tapatalk

[pennybond]

As soon as the new ECU gets here its going in!

[Jay535is]

The bodged o2 wiring probably should have been mentioned, yeah that will make a difference.
BUT, I've passed smog when I forgot to plug the o2 back in on a US 8:1 motor with an 059 and Dinan chip.

[Hit Man X]

An an MB guy, we use the plain three wire Bosch all the time too. Not a biggie, but a loose connection is...

Is there a lower CO limit? Are CO and HC all that is tested?

If so, I would lean it out a hair on that CO set screw on the AFM (5mm small guy) to drop the CO as it may pull the HC down. NOx may go up as the mixture becomes leaner, this is usually what kills the 745i on smog tests.

[pennybond]

Hi Guys,

Last night when I got home I did a little tinkering. I took out my O2 wiring and resoldered the splices of each of the 4 wires. I had continuity on all 4 wires with about 0.4 ohms of resistance before resolder which moved down to 0.2 ohms after. Didn't know if it would make a difference. I then hooked up my DVM to the O2 to look at the signal voltage and I got a weird reading....I had my meter hooked to the O2 (black) signal wire and the other DVM lead to ground. It was measuring .004 on the millivolt scale and that threw me. I ended up hooking the thing up in closed loop with the signal wire going through the DVM in series to the O2 signal ecu input pin on the opposite side of the plug and then grounded the O2 (4th wire) as this sensor does not ground with its body on the exhaust like the 1 and 3 wire do. Then I got a good signal and set the air bypass screw on the the AFM one turn out from its current position. (The AFM bypass screw was set less than 3 turns out from bottoming before I made the adjustment.) So now I just went for try number 3 a short while ago and........


PASS! CO way down, HC down a little more......Yes Hitman, they only test for HC and CO they have CO+CO2% on there as well however my car is way over the standard of 6% so that is not a part of the pass/fail.

Hey Eric were you able to find a box??? I got some Miller Lite $'s for you!

Thanks for all the help everyone! (I's still going to look at how differently the car behaves when the spare stock ecu arrives, and I'll keep you updated!)

[Jay535is]

Great news.