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2000 chevy c1500 with 4.3l has high fuel trim no codes

Just replaced the heads was clearing old codes and checking data noticed the fuel trim was 25%+ and idles rough runs fine at higher rpms

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  • billy reid Jan 21, 2013

    found that the intake plenum was leaking where the fuel injection harness went though it resealed and tested worked fine



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Posted on Jan 02, 2017

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SOURCE: engine runs rough at certain speeds 3.0 v6 flex-fuel 1999 ranger

Check and see if the EGR valve is leaking, to check this spray water on it at idle, if the water steams off the valve is leaking and is the source of your problem, also are you sure you hooked the new DPFE sensor up right? re-check it..

Posted on Nov 23, 2008

  • 101 Answers

SOURCE: 2002 Saturn idling high then drops to normal

Your 2002 Saturn car has an electrical recall .I think its the ignition modual.Owners should contact saturn @ 1-800-553-6000, Prompt 3
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Posted on Dec 16, 2008

  • 10 Answers

SOURCE: Runs rough at low rpms. Misfires but goes away at about 2000 rpm.

Sounds to me like it could be a Mass Airflow Sensor issue. Or Air fuel mixture problem. Is the harness to the MAF and Trottle control sensors hooked up right? These are just simple solutions that may work. Check all of your fuses as well. One could be blown causeing you DLC not to operate. DLC =DATA LINK CONNECTOR. Find the fuse... read the code.... solve them problem! GOOD LUCK! hope this helps.

Posted on Dec 28, 2008

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SOURCE: 99 chevy tracker is running very rough at idle

yes both of these items can cause your problems

Posted on May 17, 2009

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SOURCE: misfire code, rough idle, full tune up complete,

The black soot on the plugs means that you are running extremely rich. The fuel injectors ma test good electricly, but they are notorious for leaks. The spider-looking thing sandwiched between the plastic intake plenum and the intake manifold gets cracks in it's "legs" and leaks fuel ito the plenum area. The fuel pressure regulator is also housed in this same assembly. if the diaphram in the regulator gets a pinhole in it, it also leaks fuel into the plenum area, causing all kinds of erratic idleing, black smoke from the exhaust, and will cause your fuel trims to drop into the negative 20s.

There is a technical service bulletin covering this subject. This procedure outlines the steps required to replace the existing Central SFI Fuel System with a new MFI (Multiport Flexible Injection) Fuel System.

It is removing the injectors which are all housed in the center body of the injector assembly and replacing them with a new version where the injectors are located where the ols "poppets" used to be in the intake manifold ports. The picture below is for a V-8 engine that is covered by the same TSB.052d4ba.gif
The poppets and the pressure regulator are available individually to fix your existing fuel injection system, but I gave up on that after replacing several poppets only to have them come back in a few months with another popet line broken. I recommend replacing the whole assembly with the new and improved version. My customers have told me after doing this that the engine never ran that smooth when it was new.

The GM part number for the new injector assembly for your V-6 engine is 12568332 it is also now available at several aftermarket parts outlets.

As for the timing chain solution posted by doodieman200, all I have to say is that I have enough fingers on one hand to count all of the failed timing chains I have replaced on these engines. If you don't have a cam/crank sync code, the timing chain has definitely not slipped a tooth.

Posted on Oct 18, 2009

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1 Answer

Engine Code P0171 Logged

If Short term # is high while underway, but normal while idling, you could have a scewed maf signal. Sometimes cleaning maf with carb cleaner helps. If no intake leaks are found, and fuel pressure and volume are ok, it could be maf sensor.

Jan 18, 2016 | 2007 Toyota Hi-Ace 220

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Recently purchased. MIL light on - Scan tool Shows code P0171 $07E8 Monitor / GenericLean Trim.

First of all, what kind of car is this? Second, this is a lean code. Now, if you really have no intake leaks or restricted fuel issues, one possibility is scewed maf signal during higher rpms. If you can, monitor your Short Term fuel trim at normal highway speeds.If it is high, then and lower at idle, you may need a maf sensor.
Hope this helps

Jan 18, 2016 | Cars & Trucks

1 Answer

What is the proper fuel pressure on a 2007 chevy Colorado?

Have you looked at fuel trim

Have you looked at any scan tool data

Do all the Emission Monitors run clear

Are there any OBD Codes in any Module,
Enhanced Data, as well as Global Generic

Smoke things-- verse-- the spraying with cleaner,
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Lean or driven lean ??

Exhaust Converter worn out ?

Cylinder Misfires ?

Oct 08, 2014 | Chevrolet Chevy Cars & Trucks

1 Answer

1999 check engine light on code po170 , start car up and sometimes get hesitation when stepping on gas, ??

PO170 Fuel Trim Malfunction (Bank 1)

I'm going to guess you do No Preventative
Maintenance what so ever, or know what is needed

The Oxygen Sensors get replaced at 100,000 miles
or when they fail or when their switching times & data
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Spark Plugs-every 3 years

It costs money to work on a vehicle to learn how things are
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with no issues,then you have problems & lots of them & no
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O2 Sensors are big part of fuel trim-- IF-- you have no vacuum
leaks or cylinder misifres

An old blocked exhaust converter can be a problem

I would:
Replace the spark plugs
Replace all O2 Sensors
Clean the MAF Sensor
Replace any cat over 12 years
Check Fuel Trim
Check to see all 8 Emission Monitors run-- on a long 25
mile road test-after other work is caught up
EGR -issues
Exhaust Leaks before converter
Evap System-Leaks

Have to check & test it all-the entire vehicle
BEFORE -you replace the cat

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1 Answer

I have a 2000 isuzu rodeo love the truck all of a sudden gas mileage problem it is reallysucking back fuel what could be the cause/

Have to look at scan tool data as a start

Check for codes,fuel pressure,O2 Data,Fuel Trim
will be the first thing with that issue

Won't make a long list or guess

I will say that a repair shop will be your choice, when
you don't work on your own vehicles & ask for help.

I doubt there is any sudden change with your vehicle

Things start adding up & vehicles need the same attention,
you get, once a year from going to a doctor

Vehicle owners do less & less with vehicles today than 25
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Their just driven until almost unuseable & then are luck to get to a repair shop

Feb 02, 2013 | 2000 Isuzu Rodeo

1 Answer

Just got there codes for my 2000 323I P1250 P1188 P1189 P0304 P0173 P0170 It pass the test,anyone have any ideas ???

P0304 = #4 cylinder misfires
P0170 = Fuel Trim, Bank-1
P0173 = Fuel Trim, Bank-2
P1250 = this is invalid code for BMW
P1188 = Fuel control, bank-1, sensor-1 (pre-cat sensor)
P1189 = Fuel control, bank-2, sensor-1 (pre-cat sensor)
Vacuum leaks and/or sensor defective for the issues of the codes.
This error codes really need parts to replace. But you have to replace the thermostat first. Then clear the codes and see if any reappears,then replace defective part/s

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1 Answer

The service engine light comes on with a code P0193 "Fuel Pressure High". The fuel pressure per the monitor is 39.6 PSI (273 KPA) and the bank 2 Long Term Fuel is 4.3 compared to 1.6 for bank 1....

this vehicle has a fuel pressure sensor on the fuel rail. the sensor has a tendency to glich out on the voltage signal from time to time thus making the check engine light come on. does your scan tool have freeze frame data? if so see if the fuel pressure was high when the code set. if the pressure reads over 100 psi then the sensor is going for the fuel trim data, not an uncommon split from right and left banks if this reading is at idle. -7.0 to + 7.0 is accecptable long term fuel trim as long as both banks read rather close to one another.

Aug 13, 2011 | 2004 Mercury Mountaineer

1 Answer

4.3 Liter V-6 Idles rough when in gear, runs fine on highway.

Can you check fuel trims at idle and under load?
If fuel trim is high at low speed and load, look for a vacuum leak.
If fuel trim is high at high speed and loads, look for fuel volumn problem or restriction.
If fuel trim is high at all speeds and loads look for pcm input fault, maybe a maf sensor problem?
If fuel trim is negative low speed and load, look for fuel pressure regulator or injector leak. If fuel trim is negative at all speeds and loads check ect and iac.

If you have the spider fuel system, that system is noted for problems. key on engine off, 60--66 psi fuel pressure.

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4 Answers

Codes po174/171 cadillac deville northstar engine

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