August
2007
Air
Repair 4
E-85 & OBD II: What’s Fueling an
Incomplete Monitor?
Jeff Katz, Katz Automotive
It seems that every week we come across new bumps
in the road of emissions repair. The most recent discovery
is how fuel affects engine operation and emissions, which
raises an interesting question: Will the correct fuel in
a properly running vehicle cause monitor tests to be
incomplete? The answer may be yes.
Our vehicle was a 2002 GMC Sonoma S-10 pick-up truck,
with a 2.2 fl ex fuel engine. It had 30,000 miles, and at four
years old, it had never passed a state emissions test. The
fi rst attempt failed an OBD II test with a P0304 (cylinder #4
misfi re). It was taken to another area shop where a bad spark
plug wire was originally diagnosed and repaired. DTCs
were cleared and the truck was returned to the owner. The
MIL came back on so the truck was taken back to the shop
where it received an injector cleaning. The P0304 returned,
and was again cleared. At this point, the shop recommended
new injectors, which the customer declined. Over the next
two months, the customer tried to take the emissions test
several times and was rejected for incomplete monitor tests.
When the truck arrived at our shop, the MIL was on
with a P0304, a steady 10% misfi re only at idle, and most
monitors were incomplete. We did our normal baseline
and diagnostic tests and found that injector #4 did not fl ow
as much fuel as the other three injectors. The customer
opted for replacing all of the injectors with reconditioned
units instead of just replacing #4 with a new injector. The
misfi re and P0304 disappeared and the truck ran normally.
However, on the test drive, it would not complete any
monitors. One look at the enabling criteria in the Alldata
revealed why.
One of the enabling criteria for the monitors is an
alcohol content of less than 11% for the EVAP monitor and
15% for the other monitors. This GM fl ex fuel truck had a
data PID for alcohol content at 75%. A call to the customer
confi rmed that he was using E-85 fuel. He decided to drive
the E-85 fuel out, put in gasoline and bring it back to be
re-checked. Five days later, the alcohol content was still
24%. However, the O2 monitor was completed. Another
week and another tank of gas later, the alcohol content
read 12% and all of the monitors except secondary air were
completed. The truck was tested and passed.
This truck was driven for three months after the initial
failure. We don’t know if the customer was disconnecting
the battery to clear DTCs before testing or if he was
rejected because of incomplete readiness tests, even though
there was a P0304 DTC. The bad fuel injector resulted in
the P0304 DTC, which probably prevented some of the
monitors from enabling. After the misfi re was repaired,
the E-85 fuel prevented the monitors from running. Once
the E-85 was replaced with gasoline, enough monitors
completed to pass the test.
Jeff Katz is owner of Katz Automotive on 438 S State
St. in Elgin, IL. Phone: 847-741-7033.
SEMINAR
NO: DATE: SEMINAR NAME: LOCATION:
409 August 06 (Mon) Understanding OBDII Using Information & Technology Part 1 College of DuPage
410 August 07 (Tues) Understanding OBDII Using Information & Technology Part 2 College of DuPage
709 August 08 (Wed) Advanced Evaporative Repair Techniques Part 1 Lake County H.S. Technology Campus
710 August 09 (Thurs) Advanced Evaporative Repair Techniques Part 2 Lake County H.S. Technology Campus
202 August 13 (Mon) Emission Repair Strategies Joliet Junior College
304 August 16 (Thurs) You “CAN” Run & Set Monitors Morton College
502 August 20 (Mon) Using a DSO for OBDII Testing and Repair Verifi cation Triton College
503 August 21 (Tues) Using a DSO for OBDII Testing and Repair Verifi cation Oakton Community College
103 August 22 (Wed) Fixing Emission Problems By Reprogramming Prairie State College
203 August 27 (Mon) Emission Repair Strategies Collinsville
305 August 28 (Tues) You “CAN” Run & Set Monitors Collinsville
306 Sept. 04 (Tues) You “CAN” Run & Set Monitors Moraine Valley Community College
711 Sept. 04 (Tues) Advanced Evaporative Repair Techniques Part 1 Collinsville
712 Sept. 05 (Wed) Advanced Evaporative Repair Techniques Part 2 Collinsville
104 Sept. 10 (Mon) Fixing Emission Problems By Reprogramming College of DuPage
204 Sept. 20 (Thurs) Emission Repair Strategies Lake County H.S. Technology Campus
205 Sept. 24 (Mon) Emission Repair Strategies Oakton Community College
Register now for upcoming seminars in
August and September! Call (847) 758-3434
AUGUST
M T W T F
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13 14 15 16 17
20 21 22 23 24
27 28 29 30 31
3 4 5 6 7
10 11 12 13 14
17 18 19 20 21
24 25 26 27 28
409
COD
202
JJC
502
TRITON
203
COLLINS.
306
MVCC
711
COLLINS
104
COD
204
LCHS
205
OCC
SEPTEMBER
410
COD
709
LCHS
710
LCHS
304
MC
503
OCC
103
PSC
305
COLLINS.
712
COLLINS
