1986 vette running really rich

[grumpyvette]

"Grumpy my 1986 corvette is running very rich, at idle and runs like crap, the plugs are all sooty black, any ideas"

in most cases if your car runs rich its a malfunctioning MAF,MAP, heat or OXYGEN SENSOR,or the injectors or the fuel pressure regulator are leaking fuel, so obviously pulling trouble codes is a mandatory first step, and having a shop manual is going to be a huge help.
you can isolate the problem source if you read thru the linked info, and do a few tests
what trouble codes are displayed?


theres a huge amount of data in the links and sub links

http://garage.grumpysperformance.co...too-common-questions-can-be-found-here.12892/

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=168

http://members.shaw.ca/corvette86/FuelS ... gnosis.pdf

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=1401

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=2697

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=596

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=661

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=816

 

[GTc4]

1985 Running rich hunting for idle ??

Running fairly rich, and hunting for Idle ......1985 L98

have checked timing 6 deg BTDC, new cap and rotor wires and plugs, tps checks fine, fuel pressure ok by FSM specs, cleaned TB and maf, air filter,
PO stated at purchase new injectors and chip had been updated at some time in cars history, Coarsa cat-back exhaust,

 

[grumpyvette]

Re: 1985 Running rich hunting for idle ??

thats a nice clean looking 1985 corvette!

in most cases if your C4 corvette with a TPI, runs rich its a malfunctioning MAF,MAP, heat or OXYGEN SENSOR,or the injectors or the fuel pressure regulator are leaking fuel, so obviously pulling trouble codes is a mandatory first step, and having a shop manual is going to be a huge help.
you can isolate the problem source if you read thru the linked info, and do a few tests, set the timing, test the fuel rail pressure and test the sensors, and set the TPS sensor
what trouble codes are displayed?
any vacuum lines loose?
have you tested to see if the fuel rail pressure stays at or near 40 psi for at least 4 minutes after the engines turned off?
if you see the fuel rail pressure drop off slowly and steadily its usually a leaking injector or defective fuel pressure regulator, if it got steady fuel pressure its more likely to be a defective MAF or heat sensor or oxygen sensor

http://www.youtube.com/watch?v=_oXLUqE4Sf0

viewtopic.php?f=32&t=2697

viewtopic.php?f=32&t=168

viewtopic.php?f=32&t=1401&p=32636&hilit=sensors+camaro#p32636

viewtopic.php?f=70&t=9450&p=34592&hilit=sensors+camaro#p34592

viewtopic.php?f=32&t=1401

viewtopic.php?f=32&t=596

viewtopic.php?f=32&t=9677

viewtopic.php?f=32&t=8743

viewtopic.php?f=55&t=635

http://members.shaw.ca/corvette86/FuelS ... gnosis.pdf

 

[Indycars]

Re: 1985 Running rich hunting for idle ??


Welcome to the forum GTc4!

How long have you owned your Vette?

 

[87vette81big]

Re: 1985 Running rich hunting for idle ??

Welcome.
Beautifull 1985 Corvette you have.
Grumpy & me are both C4 owners & love them.

Do you know what brand of replacement injectors are in your '85 Corvette?
The early TPI C4'S built from 1985-88 are particular sensitive to factory flow rated injectors.
With the stock Tpi engine & computer E-prom Memory chip.

Any other known modifications to your car ?

Brian

 

[GTc4]

Re: 1985 Running rich hunting for idle ??

I don't know brand or psi of injectors the PO again stated that the plenum and runners were ported to match to improve airflow, the exhaust has been changed cat-back, and the prom changed I think the 2nd owner had done this work I am 4th owner of car it has 58000 miles!

I will check the pressure on the rail tomorrow day what should it run 40psi

also I have 3 manuals one blue loose leaf FSM, red book type FSM and Chilten which is about useless !!

 

[GTc4]

Re: 1985 Running rich hunting for idle ??

Welcome to the forum GTc4!

How long have you owned your Vette?

I have had it about 3 weeks!

 

[GTc4]

Re: 1985 Running rich hunting for idle ??

there is no trouble codes or ses illuminated! There were 2 codes when I purchased the car 33 and 34 but they were phantom from long ago "I believe" because they were cleared by me and have not returned!

 

[grumpyvette]

Re: 1985 Running rich hunting for idle ??

reading thru these links, and sub links might prove useful
running LEAN generally is caused by a vacuum leak or loose seal on an intake gasket or sensor malfunction, running rich is generally related to a mal -functioning injector, fuel pressure regulator or sensor, especially oxygen and temp sensors , but failure to correctly adjust the IAC, and TPS sensors are a common cause, get out your shop manual,and check your fuel rail pressure and fuel pressure regulator function, then pull trouble codes as a first step, reading the spark plugs and verify the ignition advance and injector fuzes and pulse duration, and verify the exhaust and catalytic converters are functioning correctly would be checked next, for good indicators of the cause of a less than ideal fuel air ratio.

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=168

viewtopic.php?f=80&t=728&p=1025#p1025

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=6011

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=3518

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=3154

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=2594

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=1942

 

[grumpyvette]

car cranks and idles for about 10 seconds and then goes dead

The car cranks and idles for about 10 seconds and then goes dead. over and over. Been sitting for about a year inside my shop. I drained the fuel and replaced the fuel pump and sock and I still have the same problem::

buy a CHEVY SHOP MANUAL FOR YOUR YEAR CORVETTE!
a logical step by step approach will lead you to the problem, youll be amazed at what youll learn reading links. use of a shop manual and multi meter can be very helpful

the oil system sensors are all potential sources for oil leaks ,and ignition problems as a defective sensor, cuts of the ignition,READ THE LINKS but the two blade sensor on the rear of the block, near the distributor base on the early c4 is a known defective part, and not only will it leak oil, if the switch is defective the fuel pump operation is random or not functional, it will also as it goes defective give intermittent or oil pressure readings that fluctuate

replacement injector pig tails are available at rock auto for less than $5 each

a vacuum and fuel pressure gauge is useful

HERES A FEW USEFUL, related bit of info and LINKS YOU MIGHT WANT TO LOOK THRU
and yes they should all read very closely) then you need a noid kit for a G.M. fuel injection system, these are basically little lights that light as the injector pulse hits them that you plug into the injector harness,after you remove the harness from the injectors, they plug into the harness just like an injector, if you try to start the engine and they blink on and off the pulse is reaching the injectors thus proving that the injectors get the pulse, each injector should get a pulse and you should see each noid light flash, if you don,t theres an electrical or wiring issue, that must be addressed.
carefully visually inspect your cars wire harness for corrosion ,loose or broken or shorting connectors or wiring, obviously getting the wrong electrical pulse, a grounded or shorted connector will cause problems.
injectors normal state is CLOSED they open only with a electric pulse, the duration of the pulse controls the volume of fuel flow
a NOID light can be used to test, the pulse is intermittent if plugged into the cars wire harness and its more likely the injector needs cleaning

http://www.harborfreight.com/11-piece-n ... 97959.html

reading thru a few links might be helpful
step #1
always ISOLATE AND VERIFY, TEST EVERYTHING ASSUME NOTHING!

viewtopic.php?f=55&t=10141&p=41021&hilit=shop+manual#p41021

viewtopic.php?f=32&t=6011&p=18597&hilit=light+timing+degree#p18597

as usual you start by pulling the trouble codes and verify the basics, verify consistent and correct fuel and oil pressure ,is being maintained, check all the fuses,check at the sensors resistance against the charts linked below,verify the heat sensors as they are particularly sensitive to failing, verify the oil pressure sensors not cutting off the ignition which is common, with defective oil pressure sensors, verify trouble codes ,put a fuel pressure gauge on the fuel rail on the shrader valve,

if the fuel filter has not been changed recently replace it, verify the fuses are good and get a noid light set to check the injectors are getting the pulse , get a multi meter and a shop manual.
chances are very good the fuel rails pressurizing but not maintaining pressure, a common issue, read the links and sub links carefully

the fuel filters located under the front pass side door area near the frame and the shop manual will go into some detail on its removal, yes your going to loose some fuel so its best to do this up on a lift or jack stands where access is easier and where you can see what your doing.
theres an arrow on the filter indicating direction of fuel flow for a reason , pay attention and do it correctly, have some shop towels and a fire extinguisher handy ANYTIME you work on fuel lines!
things you will need:

a good digital multi-meter,
http://en-us.fluke.com/products/digital ... meter.html

http://www.harborfreight.com/5-in-1-dig ... 98674.html

having a fluke multi meter and an assortment of test leads helps

FLUKE is the brand of choice but they are expensive, shop around, Ive still got the original fluke multi meter I bought in HIGH SCHOOL and it STILL WORKS Ive purchase several imported multi meters from harbor freight , in the last 10 years alone and only one still works
http://www.fluke-direct.com/shop/itemDe ... urer=FLUKE

http://www.fluke-direct.com/shop/catego ... TERS&path=
some jumper wires (not battery jumper cables)
a test light
factory service manual
and a manual for that alarm if it becomes necessary.
HERES A FEW GOOD RELATED LINKS AND SUB LINKS
viewtopic.php?f=32&t=596

viewtopic.php?f=32&t=33

viewtopic.php?f=80&t=2019&p=5367&hilit=corvette+filter#p5367

viewtopic.php?f=80&t=1470&p=3304&hilit=corvette+filter#p3304

http://members.shaw.ca/corvette86/FuelS ... gnosis.pdf

viewtopic.php?f=70&t=7309&p=24861&hilit=start+sequence#p24861

viewtopic.php?f=36&t=520&p=45063&hilit=vats#p45063

viewtopic.php?f=80&t=728&p=43477&hilit=+camaro+sensors#p43477

viewtopic.php?f=32&t=67&p=39573#p39573

viewtopic.php?f=32&t=10385&p=42943&hilit=start+sequence#p42943

viewtopic.php?f=32&t=596

 

[grumpyvette]

Re: car cranks and idles for about 10 seconds and then goes

, ANY TIME YOUR WORKING ON THE FUEL SYSTEM ITS SMART TO MOVE THE CAR OUT OF THE SHOP AND GET A DECENT FIRE EXTINGUISHER, IN REACH, ON THE OFF CHANCE YOU SCREW UP<KEEP A LARGE WET BEACH TOWEL< AND A GARDEN HOSE RUNNING ON THE LAWN NEAR BY ,YOU WON,T HAVE THE TIME TO GO LOOKING FOR THOSE ITEMS IF THINGS GO SOUTH,THINK ABOUT WHAT YOU LOOSE IF A GARAGE CATCHES FIRE!

having instant access too a 5 gallon bucket with a sopping wet soapy towel in it, near by and a running hose can do wonders at suppressing a fire, while its still small, and any time your welding or working on fuel lines its not a bad idea

 

[87vette81big]

Re: car cranks and idles for about 10 seconds and then goes

Was a nice 1985 Corvette Grumpy.
Black paint on inside turbines of stock rims.
Iron heads.
Aluminum would haveo melted.
Real Hot Furnace Inferno Fire took place there.

 

[philly]

Re: car cranks and idles for about 10 seconds and then goes

could this be an anti theft issue? i know when my buddy put the LS3 in his rx7 it had a similar issue but i dont think it idled all of ten seconds.

 

[87vette81big]

Re: car cranks and idles for about 10 seconds and then goes

could this be an anti theft issue? i know when my buddy put the LS3 in his rx7 it had a similar issue but i dont think it idled all of ten seconds.

It could be Phil.
Good Call- Diagnosis .

 

[philly]

Re: car cranks and idles for about 10 seconds and then goes

theres plenty of info online about disabling the gm VATS... on the later cars it can be done with a quick blip thru the obdII port... dont know the process for the early cars

 

[87vette81big]

Re: car cranks and idles for about 10 seconds and then goes

Jumpering the Passkey 1 Relay is one trick I have done.
Resistor is another.