I have an 88 4.9L with about 63K on the clock. After posting and reading thru various threads. I replaced IAC, TPS and O2 sensor, checked fuel pressure, and changed my fuel filter. I also cleaned the throttle body.

The problem still exists: It could be -50, the engine will start fine and run perfectly. If its about 80* it starts, stalls, starts then surges, after a few minutes things settle down and everything is fine. Restarting a warmed up engine is not a problem.

Its the first start when the weather is hot, or if it sits an hour or so on a hot day I have the same starting issues.

Any other suggestions would be greatly appreciated. I had a code 23, all codes are clear and now getting code 11.

Thanks
Frank D

 

Cold start fuel control is by the ECT and ACT sensors.
They are the same sensor packaged for their respective applications.
One may be out of tolerence when the ambient temp is warmer.
Test each with an ohm meter before starting the engine cold.
Some resistances near the cold end would be as follows.
68*= 37,000.
86*= 24,000.
104*= 16,000.
Both should be close to these values at the same temp.
If one is way out it is the problem.
Another way is to do an EEC self test initated from the engine test connector and see if the fault is detected, when the engine is lkley to do it.
Be sure their connector plugs are set on tight and are clean.
I suspect you don't see a stored code after the engine is warmed because the fault is only in only short time and clears as soon as the system tranfers to closed loop operation.
If you need to know how to do the EEC testing, I can tell you in another reply.

 

Thanks Bluegrass,

Those are 2 sensors I didn't look at. I have one of the inexpensive "count the blink" testers and the above codes were all I got. I did check the codes on a hot morning before starting it up and got the code 23. I have a TPS that is not adjustable, replaced it, cleared the code and all is good, code 11.

If you have the time to tell me how to do the EEC test you mentioned I would appreciate it. I am to the point now that if the above 2 sensors aren't too expensive I would change them, they are the originals.

Thanks
Frank D

 

If you have a test tool that uses the extra seperate lead and has a test & hold switch such as the ACTRON CP 9015, your all set.
Connect as you would for readout, set switch to hold.
Start engine, set switch to test.
The engine should respond with two high idle sequences during it's testing.
After the second hi idle test the readout will begin and go through the readout two times. Write the two diget numbers down as they come.
There are a number of other tests that you can do with this simple insturment.
It can allow the operation of all the relays, do running cylinder balance testing to three levels, test integrated cruise control on those cars that have that type.
A wiggle test that could find loose, crossed of grounding leads.
Lastly you can clear codes from memory by starting a readout and disconnecting the seperate lead while it is outputting.
There is no need to disconnect the battery to clear codes in this type of system.
Be awhere that clearing codes by power removal re-boots the computer and clears "all" the learned data as well as stored codes, so clearing with the readout is the better way.
Alway clear code after a repair and drive the vehichle about 5 miles to get the repairs integrated into the active memory before re-testing. This gets rid of 'old history' so you don't get confused about what the result of your work is.

 

Bluegrass-Thanks for the fast reply and great info.

I am using an old Sunpro CP 9015, I will go thru the book that came with it, and the info you gave me and give it a try this week.

It's not a daily driver so I have the time to really go thru it.

Many thanks,

Frank D