84 starts up very rich
Thread Starter
Intermediate
Joined: Sep 2002
Posts: 34
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From: Columbus OH
84 starts up very rich
I think i asked this one time before but here it is again, i start the 84 up and its very rich just barely runs , but as it goes into closed loop it smooths out and runs fine.i put a new fuel pump on cause it was gone , and a map sensor which helped some.I,m thinking the temp sensor in the front of the engine may be off, but i get no codes.is there any other place that could cause this to happen? the timing is right the tps has been set.new plugs , wires, cap , rotor, I do think because this has been going on for awhile now that the engine is badly carboned up, I have put two cans of carbon cleaner down the intakes, and this to has helped.used to stumble at idle but now much better there. so if i can get it to start up smooth it may be much better.
Barry Walker
Barry Walker
Pro
Joined: Dec 2008
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From: Lubbock for now, headed for Oklahoma
I think i asked this one time before but here it is again, i start the 84 up and its very rich just barely runs , but as it goes into closed loop it smooths out and runs fine.i put a new fuel pump on cause it was gone , and a map sensor which helped some.I,m thinking the temp sensor in the front of the engine may be off, but i get no codes.is there any other place that could cause this to happen? the timing is right the tps has been set.new plugs , wires, cap , rotor, I do think because this has been going on for awhile now that the engine is badly carboned up, I have put two cans of carbon cleaner down the intakes, and this to has helped.used to stumble at idle but now much better there. so if i can get it to start up smooth it may be much better.
Barry Walker
Barry Walker
I would be using some propane or spray carb cleaner and be looking for vacuum leaks. A low Baro reading at start up or low vacuum on the MAP will cause this. Put a vacuum gauge on it and tell us what you find.
Pro
Joined: Dec 2008
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From: Lubbock for now, headed for Oklahoma
Like I say, start the car and put a vacuum gauge on one of the manifold ports and let me know what it reads at warm idle. This is a preliminary check obviously. There is a HUGE list of things that can cause this, but this is some info that will help to narrow that. Like I say I need this after it has warmed up and smoothed out.
After it is warm does it have a fast idle? Does it hesitate or stumble on hard acceleration after it's warm?
Last edited by BluRay; Dec 26, 2008 at 06:34 PM.
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
The CTS should trigger the check engine light and set a code if it malfunctions. I think a check of the CTS is a good suggestion. Unless one is made of money, I don't recommend replacing anything before testing it. Besides a rich (choke) mixture when the engine is cold, the ECM regulates the idle speed and a number of other things based on info from the CTS.
RACE ON!!!
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Pro
Joined: Dec 2008
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From: Lubbock for now, headed for Oklahoma
The CTS should trigger the check engine light and set a code if it malfunctions. I think a check of the CTS is a good suggestion. Unless one is made of money, I don't recommend replacing anything before testing it. Besides a rich (choke) mixture when the engine is cold, the ECM regulates the idle speed and a number of other things based on info from the CTS.
RACE ON!!!
RACE ON!!!
This is a lot harder without live data or hands on with a multimeter....
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Michael S. Palmer
Le Mans Master
Joined: Jul 2007
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From: Tampa Florida
The last few years of C4 had multiple O2 sensors only.
Stuck open fuel injector/s may cause hard cold start issues as well. If the other CF members suggestions do not show an improvement for your issue you may want to have yours professionally cleaned (FICInjectors).
Stuck open fuel injector/s may cause hard cold start issues as well. If the other CF members suggestions do not show an improvement for your issue you may want to have yours professionally cleaned (FICInjectors).
Pro
Joined: Dec 2008
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From: Lubbock for now, headed for Oklahoma
pull the vacuum line off the fuel pressure regulator start the car and see if it leaks fuel from the nipple.
Supporting Vendor
Joined: Mar 2008
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From: Cumming Ga
Pro
Joined: Dec 2008
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From: Lubbock for now, headed for Oklahoma
You know I really missed the bus on this one. I apologize to the original poster. TBI! DOH! Of course FCI is very correct in what he is saying you should while disassembling the TBI unit remove the fuel pressure regulator and take a look at the spring in it. I have seen a couple TBI units with rotted springs that cause a whole slew of issues.
I think you would have more driveability issues if this was the case, but you really should inspect this while you have it apart for the injectors.
Side note: A timing light connected to the NO.1 cylinder and pointed at the TBI injectors is a great way to get a look at the spray pattern, and watch for drips, plus it's just kinda neat
I think you would have more driveability issues if this was the case, but you really should inspect this while you have it apart for the injectors.
Side note: A timing light connected to the NO.1 cylinder and pointed at the TBI injectors is a great way to get a look at the spray pattern, and watch for drips, plus it's just kinda neat
Melting Slicks
Joined: Jan 2005
Posts: 2,658
Likes: 4
From: Clifton Park NY
?? An 84 has a crossfire injection system, commonlly referred to a CFI. It consists of two throttle bodies and injectors, hence the term TBI. The "rear" TB unit has a built in fuel pressure regulator. There is NO vacuum line located on it. You are misleading the OP with mis-information.
You've shown already in your posts that you have very little to offer the OP, but hey so far there are 12 responses in here and 9 are yours, oughta help get your counts higher.
Here is a topview pic for you so you can see what a CFI is
You've shown already in your posts that you have very little to offer the OP, but hey so far there are 12 responses in here and 9 are yours, oughta help get your counts higher.
Here is a topview pic for you so you can see what a CFI is
Last edited by qws; Dec 27, 2008 at 10:05 AM.
Pro
Joined: Dec 2008
Posts: 658
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From: Lubbock for now, headed for Oklahoma
?? An 84 has a crossfire injection system, commonlly referred to a CFI. It consists of two throttle bodies and injectors, hence the term TBI. The "rear" TB unit has a built in fuel pressure regulator. There is NO vacuum line located on it. You are misleading the OP with mis-information.
You've shown already in your posts that you have very little to offer the OP, but hey so far there are 12 responses in here and 9 are yours, oughta help get your counts higher.
You've shown already in your posts that you have very little to offer the OP, but hey so far there are 12 responses in here and 9 are yours, oughta help get your counts higher.
Keep reading. Or do you just post to be an ***? I already covered the fact that I was in error. As for the number of counts? When you stop walking for extended periods of time let me know what it is that you find to do...until then worry about you, I've got me under control.
Melting Slicks
Joined: Jan 2005
Posts: 2,658
Likes: 4
From: Clifton Park NY
The point that I have been trying to make here is that your offering up information that is not accurate for the OP. This happens way to often on the forum and misleads the OP. They begin to look for something that is not there wasting time and there money. Posters such as CFI,Elk are experienced with CFI and know there ****. Again your posting misleading information. Before you even suggest to the OP to clean his Mass sensor I'll tell you up front that there is not one on the 84. Instead of posting all over the place why not take a moment to read and learn.... just a suggestion.
Pro
Joined: Dec 2008
Posts: 658
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From: Lubbock for now, headed for Oklahoma
Really?
The point that I have been trying to make here is that your offering up information that is not accurate for the OP. This happens way to often on the forum and misleads the OP. They begin to look for something that is not there wasting time and there money. Posters such as CFI,Elk are experienced with CFI and know there ****. Again your posting misleading information. Before you even suggest to the OP to clean his Mass sensor I'll tell you up front that there is not one on the 84. Instead of posting all over the place why not take a moment to read and learn.... just a suggestion.
Thread Starter
Intermediate
Joined: Sep 2002
Posts: 34
Likes: 0
From: Columbus OH
wow, I didn't mean to start a pissing match here guys, but thanks for the help, you all have been allot of help in the past .The coolant temp sensor is only $17.00 at corvette central I'll start there , cheap enough.the map sensor has been changed already, but the IAC are still 25 years old , they may be next if the temp sensor doesn't do it.I don't think the fuel injectors are bad they have a nice cone shape spray, and when the engine goes into closed loop the engine leans out and runs good. maybe the O2 could be changed to. anyways got all winter to work on it here , thanks guys from Ohio.
Barry Walker
Barry Walker
Melting Slicks
Joined: Jan 2005
Posts: 2,658
Likes: 4
From: Clifton Park NY
wow, I didn't mean to start a pissing match here guys, but thanks for the help, you all have been allot of help in the past .The coolant temp sensor is only $17.00 at corvette central I'll start there , cheap enough.the map sensor has been changed already, but the IAC are still 25 years old , they may be next if the temp sensor doesn't do it.I don't think the fuel injectors are bad they have a nice cone shape spray, and when the engine goes into closed loop the engine leans out and runs good. maybe the O2 could be changed to. anyways got all winter to work on it here , thanks guys from Ohio.
Barry Walker
Barry Walker
Personally I think your moving in the right direction.
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
Originally Posted by bwalker1947
The coolant temp sensor is only $17.00 at corvette central I'll start there
Barry Walker
Barry Walker
RACE ON!!!
