I have a problem that I have been struggling with from day 1 I got the car hoping that once I sort our all the unknowns it would solve by itself. As I was going to do a major restoration (build thread on TGO) I went through every bit and piece in this car including exterior, interior, electrics, electronics engine and transmission.
Focusing on my issue, I refreshed the engine by changing seals and piston rings. Bores were fine and I only gave them a quick hone. Note the engine cylinders are 0.060 oversize. As for the rest, the engine is pretty standard with standard cam and iron heads (the swirl pot ones).
I struggled A LOT with SES and Tach issues where the tach was dropping at 3000 RPM. SES was mainly related to a descreened MAF which I replaced with partial success as it was still intermittently showing MAF low code. I then burned a PROM with $6E, disconnected CSI, removed and disabled AIR Pump, removed and disabled EGR which finally led to permanent removal of the SES problem. I was so impressed that I burned another PROM ensuring I didn't mistakenly disable the error codes. Note that I do not have a catalyser and only have a Magnaflow catback system.
The only remaining issue is that especially on idle, the car smells so rich that I cant go out with the car without changing clothes as the smell sticks to your clothes, hair and everything.
All the sensors TPS, MAF, CTS, O2, Coil, Dist CAP, Knock Sensor, Ignition Module, Spark Plug wires are all new. Spark plugs are not bad either as they are brown/black[ish]. TPS is set at 0.5 at idle. Static timing (with tan cable disconnected) is set at 8* BTDC but I tried retarding and advancing a bit but it doesn't make a difference. Injectors all measure between 16.5 to 16.8 Ohms. Fuel pressure is steady at 45PSI and even tried leakdown test.
Idle is a bit lumpy probably due to the car running rich.

I am suspecting that there might be a sensor providing the ECM incorrect readings but not enough to flag an SES. I am currently waiting for an Ostrich 2.0 to fiddle around with MAF tables maybe I can workaround the issue but I am still not convinced that this is the right route. I am currently running AUJM code which should be a camaro with similar engine, heads and gear ratios. I am also waiting for a friend of mine to lend me his LM2 to try and put a figure to this rich condition.

As I am completely out of ideas I am attaching a datalog that I took in the garage perhaps some good soul can give it a look. As you will see BLMs and INTs are that way off from 128.

Can someone chime in please? My next course of action is to look at SD conversion which might not be necessary after all.

 

Forgot to say that I had to rename the attachments due to extensions being blocked.
The 6E_expanded is the xdf, 291219_A is the xdl (Datalog) and the 1227165_6E is the ads. The BIN file was uploaded without issues.

 

try checking the regulator diaphragm

 

Tried unplugging the vacuum from the regulator and didn’t see any fuel or smell in the intake.

To be honest didnt notice any change at all.

 

Yesterday i got an LM2 and strangely enough i got a lambda if 1.03 - 1.15 which is indicating a lean mixture!! Does lean also burn the eyes also?

i have also reconfirmed the ignition timing (before trying the lambda) and found out that i was advancing it to circa 15 by mistake while retightening the distributor. Now it is spot on 6.

At this point even once i get the ostrich I dont know if I should mess around with it. I also tried a datalog but the 165 started acting again disconnecting and connecting intermittent. And both times that I managed to datalog the car ran perfectly with only a very almost not noticeable hesitating while accelerating.

As a last thing, i have ordered a CSI delete kit to make sure the CSI is not leaking fuel. Dont think it is but worth a try.

if someone wants to help a bit, i will be happy posting another datalog of yesterday (5mins log) so that I get some views and opinions.

 

Do you have a hand vacuum pump you can connect to the regulator? Put vacuum on it and see if anything happens. Not getting a change disconnecting the vacuum line is a bit odd. Can you feel vacuum with your finger on the vacuum line? Do you have some way of measuring the vacuum? My regulator went bad a couple of months ago but when I pulled the vacuum line it pissed gas out the vacuum port. My comments are based on my experience with my 1991 TPI Corvette.

 

This may have nothing to do with your problem but it happened to me on the vette. The purge cannister ruptured and was dumping charcoal into the line that goes from the canister up to the purge solenoid. it got up there so far that the solenoid was stuck open. Not sure if it was pulling fumes or liquid gas through there but it ran like crap and smelled rich. May not be ur issue but something to check.

 

I appreciate your help. Will try the vacum pump with the regulator and see what it does. For sure there is vacuum and there is no gas as I have already tried disconnecting the vacuum line. Not even smell in the lines. When I say nothing changed I mean nothing that is noticeable on idle which might be a normal thing.

i am suspecting that as I found out it is actually lean not rich, that this behavior is due to having only a single rear muffler.

 

Let me see If I got this correct. it idles OK but otherwise runs like crap?

 

I'm just checking the shop manual for my vette. With the engine not running i.e. just turning the key on and off a few times the pressure should be 41-47 PSI and hold steady when the pump stops. With the engine running the pressure should be 3-10 PSI lower. From what you said earlier it sounds like that is not happening. For the regulator test my vette shop manual says with the engine running pull the vacuum line, you should get the higher 41-47 PSI then apply 10 inches vacuum to the regulator and the fuel pressure should drop 3-10 PSI. Your previous post above sounds like you may have an issue there.

 

You mentioned the LM-2 how are you using it to check the AFR? Did you add a bung someplace near the O2 sensor to measure the AFR? I also have an LM2, don't have the manual in front of me but I think I remember seeing some cautions about measuring the AFR at the exhaust pipe. You might download tuner pro or some other such program and take a look at the Block learn numbers. Oh you attached some files, I'll take a look at those.

Just looked , got an xdl file for Tunerpro?

 

Hi wsherrard

yes I am using the lm2 at the exhaust outlet using that bracket that comes with it. Re the vacuum this week I will be returning home late so cant try it out but I would appreciate you looking at the attached files. There is a short datalog file where BLM and INT can be seen. Dont look so off to me.

And re your first question, it idles fine and it runs fine. Its just strong smell in the garage when idling and am
also recently noticing that intermittently while on load pressing the gas at times it stutters feeling as if it is lean!! Didnt get the chance of trying lm2 while driving yet as I need someone to come with me to look at the handheld.

 

All I see in your files is a BIN and some text files. Is one of the text files the data log. I use tuner pro to look at the data and it wants a XDL.

 

Hey, just noticed where you are located. You a native or a displaced American?

 

Just saw ur note about the extensions. I'll take a look.

 

Well, been looking at the data. The BLM running average is running 128 most places which is normal but is below 128 in the idle area which means it's rich down there and reducing fuel. Are you running a 180 degree thermostat? Temp looks like it. I haven't looked yet but there may be some parameter related to coolant temp needs adjustment, the normal t'stst was 195 at least in my 1991 vette. Looking at the dashboard, something that catches my attention is the TPS value it's jumping around a lot, might want to check that and see that the voltage being sent to the ECM changes smoothly when the throttle is moved.

My MAP never gets as low as yours but my cam is not stock and that is probably the reason for that. Just for conversation, my TPI motor is a 4 bolt block, zero decked using a .050 head gasket. Other goodies are the ZZ6 crate motor cam, roller rockers and lifters, Edelbrock ETEC 170 heads, mating Edelbrock VORTEC style TPI base, large tube runners, ported plenum , TPIS 52mm throttle body, forged pistons and Z28 oil pump. ZF6 has been blueprinted and the clutch upgraded to a stage 2 single mass conversion from Carolina clutch. Exhaust gasses exit through the stock tube headers and a complete Magna Flow exhaust system from the headers back.

 

I am neither of them I am Maltese.

 

Thanks for your analysis!!
You have an interesting bill of materials in there far from stock.

Yes thermostat is a 180. There could be settings related to this change apart from fan on and off but the rich smell happens when cold and the intermittent hesitation while driving shouldn’t be related to any temperature I think.
Re TPS, I checked that and its a steady 0.5 to 4.3 rise. Tried it multiple times even though to be sure I checked the TPS at a point in time. I can get to 4.75v if i really push on the pedal.
You mentioned MAP. Don’t forget that the $6e is a MAF system this I do not have a MAP.

 

Regarding the rich smell, if that only happens on cold start I'd say it's normal. Mine does that as well till it warms up enough to go closed loop. Once it goes closed loop the odor goes away. I think there is some enrichment that happens when starting cold. My 91 doesn't have a heated O2 sensor so it takes a bit to close the loop.

I'm intrigued that you're Maltese. What is the language there you seem to have an amazing grasp of english. Were you educated in an english speaking country?

 

Regarding the MAP sensor Vs MAF, the BLM table has MAP and RPM on the axes. I know it's measured directly with the sensor on my car. I'm not sure on a MAF car if they measure it directly or calculate it but those are the units on the BLM axes.
I was just looking at the 6E, BIN mine is $8D. There is a volumetric efficiency table in the BIN for my speed density system which is adjusted to make tune changes. I notice there is not a VE table in the 6E BIN, do you know what is done to makes tweaks to the tune with the Mass Air Flow system? Is it the 6 MAF tables?

 

If you don't have a catalytic converter you will have an exhaust smell. The only way around it is to lean it out to the ragged edge. Unless it's a space issue I would reinstall a modern catalytic converter.

 

Well mostly its when it is cold but you could even smell it after a longish ride back in the garage.

We have our own Primary language which is Maltese (ofc). It resembles semitic (arabic) and italian with a lot of English keywords. People in Malta also speak English as we were colonised by the British from the early 1800 and became independent in the late 1960s. Education system is all built on British system.

@Tibo I think you are right. Catalytic convertor is the only way around to this. Will consider it.

 

AFAIK, if the adjustment needs to be made globally you should ideally modify the injector constant value. If there are specific areas, you take note of the Airflow values of the affected area and slightly increase / decrease the numbers until you reach your goal. $6e guys feel free to correct me here. This is all theoretical to me. Have an ostrich 2 but never tried it yet. Will have to invest in a fixed wideband to be 100%

 

Another place you might post is the Corvette forum. Seems ur not getting a huge response here. Lot of those TPI vetts have ur fuel injection setup and would probably be willing to toss out an idea or two.

 

The global adjustment is the same as I do on my speed density (S/D) setup I.E. adjusting the injector flow rate. Are the 6 MAF tables in the BIN the places you are talking about adjusting the air flow? This is similar to the S/Dsetup except the S/D has a VE table that looks very much like the Block learn table and the tweaks are made to the individual cells in the table.

"Will have to invest in a fixed wideband to be 100%" You mentioned having an LM-2 can't you use that? I have an LM-2 and had a bung for the wideband welded in just below the stock sensor when I was doing the exhaust system so I could monitor the AFR very near the same place as the stock sensor. It reads 14.7 when running closed loop. It's been a while since I had the wide band in place but it seems the AFR the last time I had it in was about 15.3 or so before it went closed loop.

I'm in the process of replacing the heater core on my vette, was driving a couple of weeks ago and the darn started spewing steam out the AC vents. Got the new one in. Now just have to finish up putting it all back together.

 

"We have our own Primary language which is Maltese (ofc). It resembles semitic (arabic) and italian with a lot of English keywords. People in Malta also speak English as we were colonised by the British from the early 1800 and became independent in the late 1960s. Education system is all built on British system."

Those Brits really got around didn't they!

 

Is your car a 1989-1992? If yes, do you have the original Multec injectors? You may want to test the ohms when they are hot. They are prone to failure. Mine was running rich like yours and that was the problem. Nothing was showing up on the scan tool and no SES light. Mechanic was clueless. Check out that video. Depending on your 02 sensor location, it could detect lean condition on one bank, have the ECM throw more fuel, but making the engine running rich on the other bank. Some cars have the 02 sensor on one cylinder if they have headers. It makes the problem even worse.


Cheers

 

Nice post SBformula.

 

Hi Sbformula.

Car is an 88 and the injectors are standard rochester 5235302 22lbs. They all measure 16.5 - 16.8 ohms but i never checked them while hot. Will check them out thanks

 

@Sbformula, Injectors checked while hot and they all have the same reading of 16.5 - 16.9.

Today I installed another '165' ECM and can say that managed to get datalogs without issues. I also installed an Ostrich and will now start looking at getting a better AFR. Believe it or not, using a handheld wideband (LM2) everytime I was looking at it while driving, it was always lean....

I have now brought down the injector constants (single and double fire) to 19lb and from the little testing that I did, it is now more in the 15.3 AFR regions. Previously it was on the 16-17 regions with at times going up to 18.

As using the LM2 is not practical, I will look into getting a fixed wideband and to be honest I was looking at the PLX with bluetooth app as I wouldn't like to add new gauges.

 

After reading the thread title, I thought that if it smells like this



it's not really a "problem", per se.

 

I am throwing this out there, you might already know all that stuff!

No matter how much you modify the tune for CL operation, theoretically, the ECM via feedback from 02 sensor will always try bringing it back to 14.7 AFR. This is with a regular 02 sensor and regular fuel (NOT with ethanol). Your wideband gauge is programmed for regular fuel, I believe, and will display 14.7 AFR when you are at stoichiometric combustion. If you have different fuel, the stoichiometric combustion AFR might be different than 14.7 (E85 fuel is 9.8 for instance). You might be able to program your AFR gauge to reflect the kind of fuel you are using. Basically for your gauge to display proper AFR you need to make sure the right fuel type is programmed into it. I am not familiar with the LM2.

The location of your wideband sensor at "exhaust outlet" is improper. It would likely get contaminated by ambient air and lose accuracy with possible exhaust leak on the way out. I would not rely on those readings.

Since the ECM via 02 sensor is always trying to bringing the AFR back to stoichiometric combustion in CL, let's say 14.7 in your case, the engine should not be rich or lean. The ECM has its limits to what it can do to bring it back to stoichiometric combustion. If the ECM reaches its limits, it will throw a SES light. If you were that lean, like your wideband gauge is saying, your engine would probably overheat and your BLM/INT would be maxed out to 160 or whatever limit you have programmed into your tune.

I know from experience that depending on the 02 sensor location, the AFR might vary on the wideband gauge even if ECM "believes" that stoichiometric combustion is achieved. It varies throughout the rpm range. Sometimes I get 13.9 and the ECM is not correcting anything. But most of the time at idle and highway cruising I get 14.7. So the ECM is fairly efficient at doing it's job. My 02 sensor reads only one bank. However, the wideband reads all banks just before the catalytic converter. For some reason, cylinder combustion on the 02 sensor bank gets leaner than the other bank. It must have something to do on how the intake charge is distributed at certain RPM and MAP range. The 02 sensor is the key. That is the only feedback the ECM gets at what it's doing.

In open loop and PE (WOT) things are different. The ECM is not getting any feedback from the 02 sensor. So it's possible to get too rich or too lean. Only a properly installed and programmed AFR gauge can tell you what is going on when in open loop and PE.

At idle in CL, the AFR gauge will swing from rich to lean constantly which is normal. The ECM is programmed to swing the AFR back and forth for proper catalytic converter operation. In CL when cruising, the ECM still swings the AFR but way faster, so the AFR gauge stays more constant. AE & DE will make the AFR rich or lean temporarily. DECEL cut off will max out the AFR gauge on the lean side (no combustion!)

IMHO, a tune does not "detune" itself. Trying retuning might not solve the problem, specially when the problem is a faulty reading to the ECM. A rich smell seems normal in open loop with cold start. If it was rich when warm in CL, you could possibly see soot coming out of the exhaust with water vapor.

I suggest you get your AFR gauge installed and programmed properly. Make sure you read all banks. That is going to tell you what is really going on. If it's rich in CL, there is something wrong with what the ECM is "seeing" and the reality. It could be many things like faulty MAF, TPS, injectors, ECM, EPROM, 02 sensor, vacuum leak, EVAP leak and so on.

I could not do any tuning or diagnostics test without my AFR gauge, specially in open loop and WOT.

Good luck!

 

Wow that is a very good explanation and all of it makes sense. Infact while in CL i was noticing that no matter what i do. The change in AFR would only for a few seconds and then return to the 16 regions which as you are saying, might not be correct after all.

i was tempted to remove the factory O2 and put in the new wideband using both its narrowband and wideband outputs but you are right, the factory O2 sees only the driver side bank so i will also get another bung and weld it where both banks meet. Note I do not have a cat.

 

Test

 

Testing my sig. Again

 

If you unplug the O2 sensor the ECM will lose its signal and make things worse. Unless the LM2 can feed a compatible signal to your ECM but I doubt it.

 

Yes almost all aftermarket widebands can simulate a narrowband signal apart from the wideband.

 

Interesting!

I have an Autometer 5779 which provides a "0-4v data output feed for ECU, data acquisition unit, or Laptop tuning". There is no 0-1v signal available to feed my ECM and simulate the 02 sensor voltage & Xcounts. It is also self calibrating and non programmable. It is to be used with gasoline only. Just read the LM2 manual and it looks like there is an analog signal of 0-1v provided. Also, "With non-cat cars, you can simply take the reading from the car’s tail pipe; " the manual says. Very interesting indeed lol.

Please update once you have it hooked up to the ECU

 

Count on it

 

Well I was reading the LM1 manual instead of LM2... Daaa! . So this is from the LM2 manual: "Alternatively you can also use the optional exhaust clamp (p/n 3728) to sample exhaust gases at the end of the tail pipe. Be aware that this method of sampling exhaust gas is prone to give false lean readings at light engine loads."

 

Interesting. I guess I should RTFM!! 😂