I just recieved my piggyback adapter today and tried it out.

My mostly stock 86E has been running rich ever since we started the original engine in 2001 (94,xxx iles). The vette has been drove less than 1,000 miles since then. Reason was it ran pig rich. Well after years of sitting up I got back to working on it last Feb. Fixed 4 codes and have done tons of troubleshooting (fixing vac leaks, installed a new Bosch O2 sensor, ect). No codes exist now. Still rich I switched out some leaky injectors of unknown lbs. with 24# Accel injectors. Still rich, so I purchased a Holley AFPR and decreased my fuel pressure from 40 psi to 35 psi and still rich. The car starts and runs fine.

I used TunerPro RT and found that everything was in range except for the knock counts were higher than they should be and the BLM stayed around 108. O2 sensor voltages jumps between .5-.8 volts.
Can give more detail.

Field Service Mode showed a rich condition with the SES light blinking 2-3 per second in accelerating and stopping conditions.

Today: I installed the piggyback adapter and seems that it connected correctly and no code. Started the car cold and it idled high longer than usual, but settled down. Exhaust smells rich though not as rich as before. Took it for a drive and it it ran about the same as before. I know it takes the ECM several trips in all conditions to learn again after the battery was disconnected. I toyed a little with the fuel pressure at idle and have it down to 34 psi though I know I should use stock pressures. Field Service Mode is now normal after observing after the first drive.

My laptop is down so I can run the scan as of now. Out of ideas.

 

If there isn't an injector issue, (too large, leaking etc.)or being able to confirm faulty 02, at 108 blm lowering the FP won't help enough and if it does you will also be adjusting the spray as well....where was it before? The tune nees to be leaned (lowered ve tables and maybe some timing)

 

You mention piggy back adapter, but no mention of what you put into it. ???????

 

Vehicle Info:
Year 86
Model Y

Broadcast ABTT

________________________________________ ________________________
Drivetrain Info:
Trans A4
Gear 3.07
Tire P275/40ZR17
Torque Convertor Stock

.

________________________________________ ________________________
Fuel System:
Injector size 24
Injector Make Accel

.
Remove Cold Start
________________________________________ ________________________
General: Constants

.
.

Thermostat 180

Injector Make Accel
Injector size 24


.

Idle Tuner's Choice (Reccomended)

________________________________________ ________________________
MAF:
.
.
No/Stock

________________________________________ ________________________
DTC's: Switches

Remove VATS
remove CAGS
remove EGR
.
.
.
.

DTC Other
________________________________________ __________________________
Exhaust:
Exhaust Stock
Catback Muffler only

High Flow Cat
________________________________________ ________________________
Engine
Intake Manifold Stock

Camshaft Stock

Duration Stock , Stock

Lift Stock, Stock

LSA Stock
________________________________________ ________________________
Head Info






Compression Stock:1
Displacement 350 CID
Rocker Stock
Throttle Body Stock
________________________________________ ________________________
MISC
.
.


Nitrous No Nothing
Wieght

 

Stock right? I'd look at other sources for a rich mix, starting with the fuel canister first (if you haven't allready) - plug it at the throttle body while observing BLMS. Ditto if it has a cold start injector, disable it while making the same observation. Disconnect the MAF - BLM'S improve? If so, it's not reading the correct air flow (and thinking about it, it's a prime suspect for what you're seeing when accelerating). There are probably a couple of others - someone else will post them.

 

OK, Lemme get this straight. You have a stock iron head, with thEGR system removed. Then installed larger injectors. Why?

Where did you find the ABTT code? I've checked the files and have not found the cross reference to this one. These are the Y codes for the 1227165 BUA, AANK, AANL, APYP, APYU, AUJM.

You might try reloading the BUA and start over.

I suggest that you contact Alvin and send him a datalog for a custom tune.

 

Hi,

If it had a problem before the injectors/tune than it will have a problem after the injectors/tune.

I'd really suggest getting us a datalog so we can sort thru it and find out whats the cause and fix.

 

 

You could try to clean your MAF just to be sure that isn't it. Use that crc maf cleaner. It got much dirt off my maf. It could be going bad too. It would be nice to borrow one and see if that helps. This is just a guess, but it never hurts to get a few ideas.

Dave

 

How do you define "rich"? Do you have a CAT? When you say the exhaust smells rich. If you are running without a CAT its going to smell rich even if the PCM is controlling to stoich. Have you pulled a plug and is it black? That would define rich. Also check the engine oil, if its been flooded, the oil can be fouled with fuel, and in that case no matter what you do with replacing chips, injectors or other parts, its going to be rich as hell.

 

Regardless of what it smells like, consistent BLM's at 108 is rich.

 

Just lean out the MAF calibration tables for the cells that are running rich.

I would start by reduce the MAF cal by about 1/2 the blm error divided by 128.

Scale the MAF tables by Approx. ((128 - (128-108)/2)/128) or 118/128 = 0.92.

This should put you in the ballpark. Fine tune from there as necessary.

 

Yes stock. I have checked the EECS system and solenoid. Also on the scan it was working correctly. Last scan I ran the MAF g/sec at 1,000 RPM was 10 g/sec. My laptop is down and I have no idea when I will get the scan running again since working on my Corvettes are at the bottom of my list (or should I say my wifes list). Thanks for the suggestions.

 

Yes, stock iron head. The EGR pipe is removed and the intake manifold and exhaust manifold is blocked off. Solenoid and EGR is still connected. ABTT is the broadcast code on the chip (didn't mention I swaped the 86E ECM with a 88 ECM). Sending a datalog was my intentions but, the laptop is down. I will need to do this though. Thanks

 

Thanks Alvin, I have checked over everything I can think of over the past 9 months for the cause of a rich condition. Sending a datalog is a good suggestion, but it might take awhile.

 

The MAF was one of the codes I got in the begining. My dad had a spare MAF and swaping it fixed the code. I have taken it off and looked at it, but a good suggestion to clean it. Thanks

 

Anything else you might have done?

 

Rich is a consistant BLM at 108 which I have and watching the O2 sensor voltage in the more rich voltage range. The exhaust smell is pretty bad. After walking around the car at idle I can definatly smell unburnt fuel. When I go back inside my house my cloths and hair smell like the unburnt fuel.

I have a stock cat now that I was told was hollow. I have never taken it off and looked, but planned on installing a hi flow cat soon. All the spark plugs have black insulators and white tips. The oil does smell like gas is in it. Though I changed oil a month ago in my rich 86 (94,xxx miles) and my normal 95 (50,xxx miles) and the 95 smelled more like gas. The exhaust smell of the 95 is normal.

I came to the conclusion that the injectors are a little too big for the stock setup, though I have read past threads where others had no problems.

 

I found a couple things I jotted down from one of the last scans ran with the TunerPro RT. Don't know if it is helpful but maybe more clues. 88 ECM and fuel pressure at this time is 40 psi.

This is at cold start up with the engine warming up at idle:

TPS .55V
Coolant temp 200*
Starting temp 76.1*
MAP 115....86 doesn't have a MAP, but it gave me this number.
MAP raw input 8
Battery Voltage 13.7v
RPM 750
NV/ratio 255 rpm/mph
MAF 8.28 g/sec
Load variable 53
Runtime 1,130 sec
Target AFR 14.73
O2 sensor ~.6v
INT 126
BLM 108
Inj Base Pulse Width 1.74 msec
Desired Idle 625 rpm
IAC 26 steps
Spark Adv/TDC 22.50
Spark Adv/Ref pulse 16.17
Knock counts 3 (after start up without driving)


This is after driving and coming to a stop and at idle:

TPS .57V
Coolant temp 201*
Starting temp 185.1*
MAP 124
MAP raw input 8
Battery Voltage 13.5v
RPM 775
NV/ratio 255 rpm/mph
MAF 8.64 g/sec
Load variable 51
Runtime 541 sec
Target AFR 14.73
O2 sensor ~.7v
INT 128
BLM 108
Inj Base Pulse Width 1.8 msec
Desired Idle 625 rpm
IAC 31 steps
Spark Adv/TDC 22.15
Spark Adv/Ref pulse 16.17
Knock counts 207

 

You had asked why I installed larger injectors 24 lb vs. 22 lb. I had read on this forum many times of individuals installing the 24 lb injectors with no problems. My intentions were to start adding modifications to the engine. Now I'm spending my $ trying to fix this. I could just buy some cheap used 22 lb injectors and have them serviced and sell the Accels.