engine stills runs rich
Thread Starter
Intermediate
Joined: Jul 2016
Posts: 28
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engine stills runs rich
Hello all. Me again. My 85 corvette still runs too rich. Way too rich. Like you cant drive it rich. I have replaced the MAFS,CTS,O2 sensor, fuel pump. I have tested the fuel injectors and inspected the fuel pressure regulator. I get 40 psi with engine running and with ignition switch on. I bought a new ECM and prom card. It wont run with calpak removed which leads me to believe the car is in limp home mode. I repaired numerous problems in the ecm harness and the TPS seems to check ok. I think this car has more electrical problems but hope that someone has maybe seen this before. Any help is greatly appreciated. Thanks
Team Owner
Joined: Jul 2004
Posts: 28,420
Likes: 3,273
From: Hartford WI
Hello all. Me again. My 85 corvette still runs too rich. Way too rich. Like you cant drive it rich. I have replaced the MAFS,CTS,O2 sensor, fuel pump. I have tested the fuel injectors and inspected the fuel pressure regulator. I get 40 psi with engine running and with ignition switch on. I bought a new ECM and prom card. It wont run with calpak removed which leads me to believe the car is in limp home mode. I repaired numerous problems in the ecm harness and the TPS seems to check ok. I think this car has more electrical problems but hope that someone has maybe seen this before. Any help is greatly appreciated. Thanks
Drifting
Joined: Dec 2013
Posts: 1,646
Likes: 17
I would suggest checking grounds. The one on the thermostat housing in particular. My 85 did the same thing and I found that the metal o-ring ground that the thermostat housing bolt goes through was broken and was barely making contact which explained why after it was warmed up on certain days it would stop running rich like a snap of the finger and ran perfect. Just my 2 cents.
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
You need to get a professional scanner or a Tech1 (or 2) that can read OBD1 and look at all the inputs that the ECM is seeing and what the fuel trim is. Checking for open/closed loop, temp input, TPS and MAP are some of the basic things you need to know to see what's happening.
If you can't do this, get somebody smart that knows what they are looking at. Or you will be messing around for the next year.
If you can't do this, get somebody smart that knows what they are looking at. Or you will be messing around for the next year.
Team Owner
Joined: Jul 2004
Posts: 28,420
Likes: 3,273
From: Hartford WI
You need to get a professional scanner or a Tech1 (or 2) that can read OBD1 and look at all the inputs that the ECM is seeing and what the fuel trim is. Checking for open/closed loop, temp input, TPS and MAP are some of the basic things you need to know to see what's happening.
If you can't do this, get somebody smart that knows what they are looking at. Or you will be messing around for the next year.
If you can't do this, get somebody smart that knows what they are looking at. Or you will be messing around for the next year.
Another possibility is the injectors are not spraying like they should and the only way to know that is with a bench test. Still, probably Multecs so might as well toss them and get rebuilds from FIC.
Thread Starter
Intermediate
Joined: Jul 2016
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rich fuel mixture.
Why did you replace all that? Was there some diagnosis done? It won't run without the EPROM because all the calibration information is there. As to the fuel pressure, I suspect it is well but what is it when you turn on? Does it spike up and hold? At what pressure? What is the WOT value? Who gave you the EPROM chip? What spec was it set to? How did you test the fuel injectors? Did they tell you what the flow rate was so we can see if it is right for the car?
The fuel pressure seems stable at about 40 psi. I will get the WOT number tomorrow. I assume that is the pressure? The fuel injectors were tested on a test bench and looked to have a good pattern. The injectors have a part #0-280 150 223 5-235 041 448 086 . Dont know the flow rate. My understanding was that the car would run on the cal-pak if something was wrong with the ECM or prom card. Thanks for the help. I appreciate it.
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Team Owner
Joined: Jul 2004
Posts: 28,420
Likes: 3,273
From: Hartford WI
The MAF sensor was bad. Someone had tried to solder the wire loop inside it.
The O2 and CTS were cheap so I replaced them.
I was told the ECM and prom card were not the right ones. I bought the ECM from cardone P/N 77-6870 and the prom card from hypertech P/N 155371
The fuel pressure seems stable at about 40 psi. I will get the WOT number tomorrow. I assume that is the pressure?
The fuel injectors were tested on a test bench and looked to have a good pattern. The injectors have a part #0-280 150 223 5-235 041 448 086 . Dont know the flow rate. My understanding was that the car would run on the cal-pak if something was wrong with the ECM or prom card. Thanks for the help. I appreciate it.
The O2 and CTS were cheap so I replaced them.
I was told the ECM and prom card were not the right ones. I bought the ECM from cardone P/N 77-6870 and the prom card from hypertech P/N 155371
The fuel pressure seems stable at about 40 psi. I will get the WOT number tomorrow. I assume that is the pressure?
The fuel injectors were tested on a test bench and looked to have a good pattern. The injectors have a part #0-280 150 223 5-235 041 448 086 . Dont know the flow rate. My understanding was that the car would run on the cal-pak if something was wrong with the ECM or prom card. Thanks for the help. I appreciate it.
Fair enough.
Cardone ECM probably is ok. The Hyperjunk part leads to THIS. That means you have a EPROM that isn't stock. Not sure what the settings are. I never trusted that sort of "off the shelf" stuff. People have torn the program apart and said all it does is turn on the fans earlier. At best no gain, at worst it introduces a variable. You might be better off getting a NOS unit on ebay or something.
If you turn the key on, it pressurizes and without engine vacuum it assumes WOT. So it should be about 43psi give or take a couple. If it holds AND you have the stock system for a while, it is good. If not, well, you need to go looking for issues in the fuel system. It might take a while like overnight and next morning it is anywhere from 0-20 for example. Again, good. OTOH, in 5 minutes if it is at 20 psi, you have issues.
Might I ask who tested them? IF it is FIC or RC Engineering or some other reputable company, they have charts to confirm what I am about to say. Look HERE.
Team Owner
Joined: Jul 2004
Posts: 28,420
Likes: 3,273
From: Hartford WI
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
I believe you are getting MAF (mass air flow) confused with speed density sensors. The MAP (manifold absolute pressure) measures pressure in manifold which bolts on top of the manifold.
If for some reason the 85 does not use a MAP, then its just my lack of specific knowledge of the 85.
Team Owner
Joined: Jul 2004
Posts: 28,420
Likes: 3,273
From: Hartford WI
I was just throwing out some starting suggestions.
I believe you are getting MAF (mass air flow) confused with speed density sensors. The MAP (manifold absolute pressure) measures pressure in manifold which bolts on top of the manifold.
If for some reason the 85 does not use a MAP, then its just my lack of specific knowledge of the 85.
I believe you are getting MAF (mass air flow) confused with speed density sensors. The MAP (manifold absolute pressure) measures pressure in manifold which bolts on top of the manifold.
If for some reason the 85 does not use a MAP, then its just my lack of specific knowledge of the 85.
Drifting
Joined: Mar 2013
Posts: 1,952
Likes: 239
From: Venice Cali.
1985 is maf, I would agree with post above to check the things that control fuel ratio.
The water temp sensors on the front of the engine.
Also all connectors need cleaning I've noticed on mine.
The water temp sensors on the front of the engine.
Also all connectors need cleaning I've noticed on mine.
Last edited by xrav22; Nov 29, 2016 at 03:06 PM.
Team Owner
Joined: Jul 2004
Posts: 28,420
Likes: 3,273
From: Hartford WI
I'm a little nervous about the connections. Sometimes the connection part gets brittle so be careful and use a bit of dielectric grease
Thread Starter
Intermediate
Joined: Jul 2016
Posts: 28
Likes: 0
85 fuel issue
Soon as the wire is broke, it is junk so good call on that one.
Fair enough.
Cardone ECM probably is ok. The Hyperjunk part leads to THIS. That means you have a EPROM that isn't stock. Not sure what the settings are. I never trusted that sort of "off the shelf" stuff. People have torn the program apart and said all it does is turn on the fans earlier. At best no gain, at worst it introduces a variable. You might be better off getting a NOS unit on ebay or something.
If you turn the key on, it pressurizes and without engine vacuum it assumes WOT. So it should be about 43psi give or take a couple. If it holds AND you have the stock system for a while, it is good. If not, well, you need to go looking for issues in the fuel system. It might take a while like overnight and next morning it is anywhere from 0-20 for example. Again, good. OTOH, in 5 minutes if it is at 20 psi, you have issues.
Might I ask who tested them? IF it is FIC or RC Engineering or some other reputable company, they have charts to confirm what I am about to say. Look HERE.
Fair enough.
Cardone ECM probably is ok. The Hyperjunk part leads to THIS. That means you have a EPROM that isn't stock. Not sure what the settings are. I never trusted that sort of "off the shelf" stuff. People have torn the program apart and said all it does is turn on the fans earlier. At best no gain, at worst it introduces a variable. You might be better off getting a NOS unit on ebay or something.
If you turn the key on, it pressurizes and without engine vacuum it assumes WOT. So it should be about 43psi give or take a couple. If it holds AND you have the stock system for a while, it is good. If not, well, you need to go looking for issues in the fuel system. It might take a while like overnight and next morning it is anywhere from 0-20 for example. Again, good. OTOH, in 5 minutes if it is at 20 psi, you have issues.
Might I ask who tested them? IF it is FIC or RC Engineering or some other reputable company, they have charts to confirm what I am about to say. Look HERE.
Thread Starter
Intermediate
Joined: Jul 2016
Posts: 28
Likes: 0
still runs rich
Hello all. My fuel injectors are bosch 280-150-223 that flow 21.35 lb/hr. at 36 psi. It definitely wont hold 40 psi overnight. I will time it tomorrow. Where does the vacuum hose to the FPR come from? The car came with an ecm from a 91 cadillac and the prom was from a 85 firebird HLM designation. The car wont run on the ECM i bought at all. Any help is greatly appreciated. Also I am considering a carb if i cant get it to run right. Thoughts?
Team Owner
Joined: Jul 2004
Posts: 28,420
Likes: 3,273
From: Hartford WI
Hello all. My fuel injectors are bosch 280-150-223 that flow 21.35 lb/hr. at 36 psi. It definitely wont hold 40 psi overnight. I will time it tomorrow. Where does the vacuum hose to the FPR come from? The car came with an ecm from a 91 cadillac and the prom was from a 85 firebird HLM designation. The car wont run on the ECM i bought at all. Any help is greatly appreciated. Also I am considering a carb if i cant get it to run right. Thoughts?
You might check on some programming boards if the 91 Caddy has the right ECM. Not sure what the 85 F-body eprom does.
I don't know if you want to do that. Without the ECM, you might have to wire gauges. For a pure race car, no problem. How did you come on that ECM and EPROM combo? Did someone who checked calibration tell you that? According to Tunerpro site, you should be using ECM part number: 1227165 and your broadcast code should be, according to ChevyThunder: HLP