new engine won,t idle



new engine won,t idle

Postby grumpyvette » December 7th, 2011, 7:23 pm

" hey grumpyvette? my new engine Wont Idle after rebuilding my 90 vette auto
Ok, so I went to my builder today and sugested that he contact PCM for less for a newly tuned chip, and his response was that PCMforless is who he has been using, and are the ones who told him to put in a smaller cam. build sheet says:


http://redlinedetection.com/pages/video/

bored .030 balanced
full recon on heads 2.02 stainless 1.6 ex 3 angle bowlhawged milled .0019
103523750571 eagle crank
sir7000bblw eagle full float rods h90cp
0.30 speed pro pistons 9.5-1
08-408-8.comp roller cam 2148 roller lifters prw roller 1.5 rockers direct fit headers

they also put in a new water pump o2 sensor, oil sensor and radiator.

The car wont Idle without having the idle turned way up, and it has less power then when it was stock."


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yes I know everyone wants an instant correct answer, the problem is it takes accurate testing to locate your problems source and guessing is a waste of time and money,
yes it will take you some time but it will be worth the effort to read thru the links and sub linked info below look I know its going to take some research, and testing, no I,M not just answering your question but covering the basic problem, guys seem to get over whelmed, its simply going to require a logical; step by step process of testing to locate the source of your problem, Im well aware is frustrating,its time to break out the multi meter, vacuum gauge and timing light and a shop manual. your particular issue sounds like timing or a vacuum leak but testing will prove or disprove the problem,.
randomly replacing components is a rather expensive and far from effective way to fix the issue

and while reading links <AND SUB LINKS) might be painful , but it will lead you to the source of the problem
you need to get a shop manual, and multi meter and start checking each stage of the process


If you look over the threads on this and most other sites related to cars you'll see a recurring theme,and that theme is related to the total frustration many guys seem to feel when the car engine won,t run or run correctly, and for some reason the average response is to start throwing random guess work list of new parts at the problem, rather than stepping back, and doing a logical list of tests and braking out the shop manual, multi meter, vacuum and fuel pressure gauges and a timing light and using the tools too isolate the source of the problem by testing sensors,electrical connections and function of each related component , AFTER RESEARCHING the problem.
the basics remain the same
you need compression
which means the rings and valves must seal the cylinder and the cam lobe timing must be CORRECTLY indexed to the crank rotation
YOU NEED FUEL
which means the carburetor or injectors on the engine must get an adequate flow and consistent pressure, and must atomize that fuel and mix it with air flow in the proper ratio.
YOU NEED ignition
which means the spark plugs must fire, or arc, at the proper time in relation to piston location as the crank and cam rotate,with a spark or adequate heat and duration to ignite the compressed fuel air mix
YOU NEED AN UN RESTRICTED AIR FLOW ]
which requires that both the intake manifold and exhaust system allow near unrestricted flow into and out of the engine
YOUR ENGINE MUST BE PROPERLY LUBRICATED
which both reduces heat and wear and keeps the engine from seizing up, or getting into detonation or having parts fail from heat stress
YOU NEED A COOLING SYSTEM[
to maintain the engines operational temperature in its intended range, and reduce wear and parts failure so the lubrication and cooling systems, operate together.
ALL THE SENSORS MUST WORK, SO CHECK YOUR ELECTRICAL CONNECTIONS, FUSES AND GROUNDS

if one or more of these functions or the sensors that control these functions fails your engine won,t operate correctly so its your job to isolate the problem


viewtopic.php?f=55&t=1820&p=4706&hilit=edelbrock+carbs+1406#p4706

viewtopic.php?f=32&t=1401

viewtopic.php?f=44&t=6082&p=18927&hilit=testing+coil#p18927

viewtopic.php?f=80&t=728&p=1025&hilit=sensors+camaro#p1025

viewtopic.php?f=32&t=2697

viewtopic.php?f=70&t=1015

viewtopic.php?f=70&t=875

viewtopic.php?f=70&t=294

viewtopic.php?f=44&t=6669&p=21352#p21352

viewtopic.php?f=70&t=2798

viewtopic.php?f=70&t=1701

viewtopic.php?f=70&t=3301

viewtopic.php?f=70&t=251

viewtopic.php?f=70&t=4683


always drop back to the basics
you can,t guess you need facts
WHAT CONVERTER STALL SPEED ARE YOU USING?
did they actually degree in the cam?
whats your ignition timing curve?
have you CORRECTLY adjusted the valves?
whats each cylinders compression?
whats the vacuum at idle?
are the injectors all reading the same ohm resistance?
whats your fuel pressure?
WHATS YOUR VOLTAGE
look theres easily two dozen more things to verify, but once your dealing with PROVEN FACTS vs GUESS WORK your going to locate the true cause far faster, you may not want to hear this but a shop manual, and some testing will PROVE to you whats causing the problem so you can rationally , and based on facts proceed to locate, isolate and correct the cause, any other routes random guessing

yeah! I know you would rather not read thru the links and sub links......thats on reason theres so few guys that are good at trouble shooting and diagnosing these problems, and why some shops get away with doing crap work and charging big bucks



How to tune a carb with a vacuum gauge.
http://www.centuryperformance.com/forum ... cuum-Gauge

How to interpret a vacuum gauge.
http://www.secondchancegarage.com/public/186.cfm


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

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

http://forum.grumpysperformance.com/viewtopic.php?f=80&t=728

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

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=1773

http://forum.grumpysperformance.com/viewtopic.php?f=55&t=606&p=7969&hilit=noid#p7969
what your 100% sure is correct may not be!
I recently had a guy over to do a minor test & tune on his car,(name with -held due to protecting the guys good name )no hes not on this site hes a neighbor) (an 1985 vette) because it didn,t run very well, (It idled like crap,after a cam upgrade)now it had a fairly normal low rpm power curve but it failed to pull well after about 3500 rpm
he was convinced it was an injector issue and wanted me to test and replace the injectors if required, or that the cam he had installed was defective
I told him the first step was to DROP BACK TO THE BASICS
and verify everything as we proceeded
but he was 100% convinced he had done every step in the cam install correctly, and wanted me to concentrate on finding the defective injector(s).
step one
I verified his engines TDC on the timing tab and damper
(the result was that the damper marks were off by about 4 degrees) I asked if he had degreed in the cam (knowing the obvious answer)
then I installed an adjustable timing tab and told him he was required to buy a replacement functional damper
STEP TWO
I suggested we adjust the ignition timing , and we got that correct to factory specs
STEP THREE
I suggested we adjust the valves,(he was 100% convinced he had that correct)
well I pulled the valve covers which is not easy with the alternator in the way) and after adjusting them at idle found they were all over the map on preload, (some were 1/4 turn in from zero lash some were 1.5 full turns in) he had adjusted them by spinning the push rods between his fingers, feeling for resistance after seeing the intake valve close., and I noticed one valve spring was cracked,(replaced that but had to use a stock spring so I strongly suggested he buy a full new set, I looked up the correct part number (YEAH! I KNOW! the chances he,ll follow thru and buy and install them are about as good as my wife buying me a MISTRESS for my birthday)
STEP FOUR
once the valves and timing were adjusted I checked for fuel pressure and found, that the fuel pressure was 36 lbs but dropped rapidly if the engine was shut off, it turned out the 9th injector was leaky(luckily I had a spare from a salvage yard)
step five
I checked for vacuum leaks and found the lower left runners were not sealed correctly(that was corrected with a new gasket.
step six
I metered the ignition wires for resistance (they all sucked)and checked the firing order,(ok) looked over the rotor and distributor cap (absolute joke, corroded, (white crumbly aluminum contacts) looked to be several years old and evidence of getting wet at times) and verified plug gap (again they ran from .037-.051) I dropped them all to .043, now the car ran a good bit better, we discussed pulling the timing cover and verifying the cam timing but that's a good deal more work, so for now we will assume its close until we get the time to check
step seven
I started verifying battery voltage, fluid levels, and sensor connections , and found the o2 sensor wire had obviously been at least on occasion touching the exhaust in the past as it was floppy loose ,as the insulation was melted, and the knock sensor was not even connected as the wire that goes to it had no connector.

if you think this was a worse case deal its not!
most older corvettes I see and some I work on, come into the shop only after the owners get tired of chasing intermittent problems, or find that the car runs like crap and only then decide to research the cause.
look we all have problems,wear issues and most of us work on very tight budgets, but you can,t jump to conclusions or assume anything, the only way to correct problems is to drop back to the basics and VERIFY every thing STEP BY STEP,WITH A BASIC CHECK LIST and a few tools like a timing light, a shop manual and a MULTI meter are mandatory



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

http://forum.grumpysperformance.com/viewtopic.php?f=50&t=609

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

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

viewtopic.php?f=55&t=1475&p=3325#p3325

http://forum.grumpysperformance.com/viewtopic.php?f=70&t=875

http://forum.grumpysperformance.com/viewtopic.php?f=62&t=882&p=1390&hilit=+propane+leaks#p1390
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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