Question: Another E4ME question

[bradfordsvettes]

how are the o-ringgs onthe air bleed valve on top of the carb that also can not be bottomed out all the adjustments are intermingledis your thermostat ok you also need a certain engine temp before closed loop is achieved. I may not understand your whole issue here Steve

 

[LannyL81]

I replaced the O rings in the idle air bleed valve when I put the rebuild kit in. Was not really pleased with the fit and I should try replacing them again. I used the "J" tool to set the idle air bleed valve, but not able to do the final adjustment until I get into closed loop.

Another odd thing: when I removed the pump lever and ran the engine...I got nice throttle response..BUT I did not get a Check Engine lite for no TPS output. With the pump lever out, the TPS is not moved and I should have gotten an error, in fact the engine should not have run very well as the timing should not get advanced really well. I know it will some from the limp home advance feature in the 7 pin ignition module.

Wonder now if I have a bad computer or something???

 

[bradfordsvettes]

I do believe the tps only tells the computer where the throttle is. at idle it should be approx .5volts or a little higher full throttle should be close to 5 volts the map sensor is what really tells the compuer how much load the engine is under and affects timing but they are all used for the calculation Steve a scan tool for data would be a big help for you

 

[Sensei]

The computer scan tool you need is an OTC Monitor 2000.

eBay Motors: OTC SYSTEM 2000 DIAGNOSTIC SCAN TOOL (item 110314926989 end time Nov-29-08 17:52:06 PST)

Keep an eye out, I got one off ebay for $25.

If your MC solenoid is clicking, I think you are in closed loop. My computer says when mine goes into closed loop and I still get no varying dwell. Oh well. Mine runs a little rich, but I think it is because my cam gives less vacuum than stock, fooling the engine into thinking it is under load. It is not rich enough to cause any problems, in fact, it runs great!

If you have a new brass float, it may be your problem. I went to NAPA for a float and their listings for an '81 vette were wrong. I had to match up one to my original. The originals were nitrophyl, and that's what you want. I can't imagine anyone making a brass one that would be right. the wrong float could cause the fuel problems you describe. Do you still have your original float?

God bless, Sensei

 

[motorman]

The computer scan tool you need is an OTC Monitor 2000.

eBay Motors: OTC SYSTEM 2000 DIAGNOSTIC SCAN TOOL (item 110314926989 end time Nov-29-08 17:52:06 PST)

Keep an eye out, I got one off ebay for $25.

If your MC solenoid is clicking, I think you are in closed loop. My computer says when mine goes into closed loop and I still get no varying dwell. Oh well. Mine runs a little rich, but I think it is because my cam gives less vacuum than stock, fooling the engine into thinking it is under load. It is not rich enough to cause any problems, in fact, it runs great!

If you have a new brass float, it may be your problem. I went to NAPA for a float and their listings for an '81 vette were wrong. I had to match up one to my original. The originals were nitrophyl, and that's what you want. I can't imagine anyone making a brass one that would be right. the wrong float could cause the fuel problems you describe. Do you still have your original float?

God bless, Sensei

you are correct about the float as the brass has a different buoyancy than the stock float so the factory float setting would not be correct for a brass float. make sure you do not have excess fuel pressure caused by a plugged return line from the fuel pump to the tank

 

[RC81]

Mine been driving me nuts as well. In trying to get a varying dwell this week, I changed out the ecm, coolant sensor, 02 sensor and tps. Still varying and no check engine light. Mine runs good as well. Who knows...

 

[LannyL81]

I do not have the original float, but can sure get one. Not sure I agree / understand the problem with a brass float. As long as I have it set at the right height, the buoyancy should not make any difference.

I put an O'scope on the MC solenoid and it showed a steady 30millisecond pulse width. The MC solenoid is moving.

Next step is to see if the O2 sensor is really putting out a signal. Hopefully not and then I have found my problem with open / closed loop.

Carb settings acted different yesterday. With the idle mixture screws at 1 turn out from seat, I had fuel dripping out the primary nozzles. So I can stop that by turning the idle mixture screws out another 2-3 turns. Also, I had to put the pump lever back on to get the engine to rev-up this time. Idle air bleed screw settings still has no affect other than when all the way down or almost all the way out. Put it back using the J tool.

The fun continues.

RC81: Did you get your dwell to vary now?????

 

[GerryLP]

Lanny,

Have you allowed the engine to warm-up sufficiently, so that the operating temperatures have been reached and the temperature sensing gives the right signal to the computer?

In these days of advances and tweaks, perhaps the engine has not reached the correct temperature. If you have a lower setting thermo-stat, it would take the engine a little longer to warm-up, for it is sending water to the radiator to cool earlier than usual.

I have had mine not hunt sometimes, and I have always fixed the problem by letting it idle a bit longer.

PLEASE BE SAFE, AND MAKE SURE THAT ALL 4 WHEELS ARE BLOCKED. THE IDLE MIXTURE ADJUSTMENT CHECK IS DONE WITH THE VETTE IN "DRIVE", everyone, please be safe...

Here is some reference material I had up-loaded to the CAC.

Page 126 of AC-Delco SD-100A
(in step 7 for the E4ME, it is refering to the TPS voltage value found in the table of values in page 153 below)

Page 134 (the small paragraph at end starts the procedure on page 135).

Page 135

Page 138 (procedure "8" is for the E4ME)

Page 139

Page 140

Page 153

This is the applicable legen for the number codes in the applicable columns for the page 153

I hope this helps. Check your connections. Specially the water temperature sensing connector.

GerryLP:cool

p.s. If these pages are hard to read or print, go to the Member's galleries under the Off Road lounge, and you'll find my up loaded images.

 

[RC81]

I do not have the original float, but can sure get one. Not sure I agree / understand the problem with a brass float. As long as I have it set at the right height, the buoyancy should not make any difference.

I put an O'scope on the MC solenoid and it showed a steady 30millisecond pulse width. The MC solenoid is moving.

Next step is to see if the O2 sensor is really putting out a signal. Hopefully not and then I have found my problem with open / closed loop.

Carb settings acted different yesterday. With the idle mixture screws at 1 turn out from seat, I had fuel dripping out the primary nozzles. So I can stop that by turning the idle mixture screws out another 2-3 turns. Also, I had to put the pump lever back on to get the engine to rev-up this time. Idle air bleed screw settings still has no affect other than when all the way down or almost all the way out. Put it back using the J tool.

The fun continues.

RC81: Did you get your dwell to vary now?????

I never did get my dwell to vary. When cold its over the 20 degree mark then when warm - I assume when it goes to closed loop - it drops to under ten and stays. If I rev the engine it does go back up then falls again. I have no check engine light come on and once warm the car runs great. Dont know how to make the dwell perform per the manual.

 

[LannyL81]

GerryLP; Yep, pretty sure the car is warmed-up....I let it idle for a good 5-7 minutes before I start trying to make adjustements.

Thanks for the info....

I did put the O Scope on the O2 sensor output yesterday and unless I was not making contact, I got nothing. So I am going to try connecting directly to the O2 sensor output. I also have a new O2 sensor ready to go in and try. Duh...that I had already done this....

Idle mixture is still way too rich as I have to hold the choke plate open when I first start-up or the engine will die. Takes less than a minute for the electric choke to open all the way.

I will also check the coolant sensor resistance at hot...this is a new sensor, but that does not mean it works. At cold the resistance is about 3k ohms...

Have to wait until later this morning before I can fire it up....it is a bit loud with the sidepipes and all......

 

[LannyL81]

SUCCESS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The problem was the O2 sensor, it simply did not get hot enough. I tried a new O2 sensor...no output. I temporary connected a heated O2 sensor and within a minute I had a varying dwell. Took a bit of time adjusting the idle mixture screws and the idle air bleed screw to get the dwell to average at 30, but it did. Now I just have to figure out where to wire-in the switched 12 volts for the O2 heater. It is going to have to stay on all the time, so I plan on adding additional resistance to the circuit so I do not burn-out the O2 sensor.

I ended-up with the idle mixture screws at one turn out, which tells me that something is still not quite right here. Engine is getting fuel from somewhere and causing the rich cold start condition with the choke plate closed. So still more "to do" but getting it closer.

Thanks for all the help...
LannyL81

 

[bradfordsvettes]

that sensor is designed to run on 12 volts without any issue if you add resistance it may not heat up at all or not get up to temprature hnoes which is at least 600 degrees if my memory serves me right.12volts swithed is all you need and only in the run position Steve

 

[LannyL81]

Steve,
I thought that engine computers would cycle the O2 heater, not keep it on steady. I thought I had read this somewhere. The O2 sensor I have has a 15.7 ohm heater, highest resistance I could find. I have four 10 ohm 2 watt resistors in parallel which gives me 25 ohms. The O2 sensor itself would dray 0.794 amps. With the 25 ohms added, current drops to 0.294 amps...which may not be enough to keep the O2 sensor hot...will have to try it. I do not want to burn out the heater as this O2 sensor is about $50...not something I want to replace after every drive or so.