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L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

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Old 06-18-2005, 10:01 PM   #1
gtplus2
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Default Crossfire to carb transplant? YES/NO...

Okay here's the story, I have been although the archives and cannot find squat on this topic. So here is My problem, 1984 Vette with original crossfire set up, no codes and constantly is gas fouling plugs. With the air lid off and running looking at the injectors operate I can seen the injectors working and can see visible fuel and droplets, I was told from an outside source that at idle fuel delivery should be almost invisible or light "fog" like, true or false? Next issue... replacement injectors for this year are very difficult to get true or false? I am finding that they are hard to get! Okay I am just full of questions, just one more... Would it be better to pursue replacement injectors or do a carb and intake swap? If so please be specific as to what to use. Thanks for Your input!
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Old 06-19-2005, 01:29 AM   #2
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Checkout Crossfire Injection Vault. Tons of info on Crossfire vehicles.

I got my injectors here -> http://www.fuelinjectorsdirect.com/default.asp. I have purchased a set of Cop Car Injectors and my 90 pouders for my 383 equipped 84. I am using the XRam and 2 inch TBs.

Are your plugs fouling with gas or oil. I am assuming gas. There are many reasons to have the engine run rich. First thing I would think of is the MAP sensor or CTS (coolant temp sensor located in the front of the manifold). Where is your fuel pressure at? How many miles?

There should not be a "fog" at idle. FALSE ! You should see a good cone shaped spay pattern. The easiest way to tell is to use a timing light and point it to the injectors at idle.

Personally I would keep the Crossfire or at least check out the Crossfire forum above before you decide to swap to a carb. Don't take this the wrong way but get to know how your 84 works. When I bought mine I did not know squat... But now I have a 383 in it. I have been to the strip once (last weekend and I am not done tuning) to see where I was at and I turned a 13.43 @ 102.5 which aint bad considering no dyno time and I have only been gathering data with WinALDL. I justi got my WB02 so I will be able to make further advancements with the tune. There is a guy in Australia that is running 12s --- so it can be done. Invest a little time in our Crossfire doing research and you just might come to appreciate its simplicity like others.
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Old 06-19-2005, 02:16 AM   #3
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Quote:
Originally Posted by elkabong
Checkout Crossfire Injection Vault. Tons of info on Crossfire vehicles.

I got my injectors here -> http://www.fuelinjectorsdirect.com/default.asp. I have purchased a set of Cop Car Injectors and my 90 pouders for my 383 equipped 84. I am using the XRam and 2 inch TBs.

Are your plugs fouling with gas or oil. I am assuming gas. There are many reasons to have the engine run rich. First thing I would think of is the MAP sensor or CTS (coolant temp sensor located in the front of the manifold). Where is your fuel pressure at? How many miles?

There should not be a "fog" at idle. FALSE ! You should see a good cone shaped spay pattern. The easiest way to tell is to use a timing light and point it to the injectors at idle.

Personally I would keep the Crossfire or at least check out the Crossfire forum above before you decide to swap to a carb. Don't take this the wrong way but get to know how your 84 works. When I bought mine I did not know squat... But now I have a 383 in it. I have been to the strip once (last weekend and I am not done tuning) to see where I was at and I turned a 13.43 @ 102.5 which aint bad considering no dyno time and I have only been gathering data with WinALDL. I justi got my WB02 so I will be able to make further advancements with the tune. There is a guy in Australia that is running 12s --- so it can be done. Invest a little time in our Crossfire doing research and you just might come to appreciate its simplicity like others.
Okay this is where I am at, I ran a compression test while engine was still warm. All of the cylinders read 145/150 the cylinder that was suspected read 160, most likely from fuel excess. Car has 101k on it and performs flawlessly with a fresh set of plugs in it, 60ft. of rubber easy! All the plugs when pulled where black, but clean on the very end of the electrodes except on the one that was all black and wet. This plug turns black and dull when I allowed it to atmosphere dry. Tail pipes are black and sooty and leaves black exhaust marks on the ground at idle. The car threw a code 15 last week and that has been dealt with, "coolant temp switch" located on the passenger side towards back of head. Cleared comp. and no more codes. Can You be more specific as to MAP sensor or CTS (coolant temp sensor) CTS that You refer to, isn't that what I just changed? But what I changed was in the rear of the passenger side head?... I CERTAINLY concur w/You as to leaving the crossfire in place and am quite willing to learn all I can about it!
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Old 06-19-2005, 02:56 AM   #4
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There are actually three coolant temp sensors. The one one the passenger side controls the fan, the one on the drivers side is for the temp gauge. The other one is on the front of the manifold and that is the one the ECM uses for temp readings. It is common for the wires to break or fray because of age. If the ECM is gets a low temp reading it will think the motor is cold (cold start up condition) and dump more fuel. The bad MAP sensor (located above the power brake booster) will also cause more fuel to be added.

Here are the sensor locations the one code 15 refers to is #9. The coolant temp sensor the ECM uses. I don't know why the code was cleared as you indicate but I suspect you still have a problem based on the plugs still fouling. You will need to remove the belt and air pump to get to it and maybe the waterpump pulley. Be careful of the connector and the cap that fits over the sensor it is more than likely very brittle and will break easily.

Click the image to open in full size.
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Old 06-19-2005, 03:27 AM   #5
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The original 84 CTS (front of manifold) sensor connectors are dodgy. They are easily recognised as being a 'squeeze to remove' type connector with 2 concentric terminals. When you buy a new one these days, they come with a new style weatherpack connector with 2 pins side by side, and a pigtail you need to splice onto your existing wires. Its a very common fault and easily rectified. It makes you car run rich and foul plugs because the ECM sees the engine as being at sub-zero (degC) temps and therefore richens it right up, like a choke..

Also, if you have been running like this for some time, you have probably fouled the oxygen sensor also, and it may be getting a bit lazy, and contributing to the prob...
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Last edited by ben73; 06-19-2005 at 03:30 AM.
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Old 06-19-2005, 11:38 PM   #6
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UPDATE; We did locate and remove sensor in question, Also gave it the ohm check. 1000 ohms cold, Hot still read 1000 ohms. Chances are good that We have found our problem, Can't THANK YOU GUY'S enough for You help and tips, Will attempt to get a new one tomorrow at Kendell Chevy. Will also update again after We get it to that point. THANKS AGAIN!!!
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Old 06-20-2005, 03:01 AM   #7
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Quote:
Originally Posted by gtplus2
UPDATE; We did locate and remove sensor in question, Also gave it the ohm check. 1000 ohms cold, Hot still read 1000 ohms. Chances are good that We have found our problem, Can't THANK YOU GUY'S enough for You help and tips, Will attempt to get a new one tomorrow at Kendell Chevy. Will also update again after We get it to that point. THANKS AGAIN!!!
glad to hear you took your time to diagnose the problem and track it down.
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Old 06-20-2005, 11:59 PM   #8
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i want to thank everyone in this post for the helpful information on getting this issue taken care of, my father is gtplus2, and it was my 84 that we were trying to get straghtened out


thank you
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Old 06-21-2005, 12:23 AM   #9
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So a new temp sensor fixed it?
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Old 06-21-2005, 12:36 AM   #10
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yup,fixed it, and it even fixed its little hesatation


now my mileage is way up, @ 55MPH on the cruise my instant MPG is at about 28-32, and my average is about 26.5 MPG




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Old 06-21-2005, 12:39 AM   #11
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Too easy! Try getting that MPG with a carb swap
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Old 06-21-2005, 12:52 AM   #12
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Quote:
Originally Posted by ben73
Too easy! Try getting that MPG with a carb swap


no kidding, i wasn't thinking about MPG at the time
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Old 06-21-2005, 12:52 AM
 
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