88 Camaro 5.0 tbi grief

I might check with your local wrecking yard for a computer first. Also check your ecm grounds as a bad ground could cause erratic readings and misscue by the ecm.  

I would start by checkin the reference voltage to the tps sensor, it should be 5 volts...that having been said "clear flood mode happens with the engine off-key on, triggered by depressing the accelerator peda to the floor three times within three seconds. it could be possible that the ecu di either A.) losing ground (as the other reply said) B.)losing power for a split second when the transmission is placed in gear C.) the wiring for the tps may be shorting out and sending erronious information to the ecu.
the thread did not show or you did not list the year of the truck you got the ecu from...was it a manual or auto? do you get code 12 when you scan the codes? i know that it sounds like i am asking stupid questions but i converted a 91 caprice cop car to a 5 speed, its speed sensor was WAY off (either that or my driveway really did become 311 miles long) i had no drivability issues other than the computer would tell me that  there was a "High vehicle speed in park indicated" as i recall most early model tbi ecu's dont look at the gear selected (as evidenced by the above trouble code) so i would look really closely at the wiring harness/ computer plug to see if your problem lies there.  

The engine and ecm are out of an 88 Camaro  5.0lt vin E that had a 5 speed.

I don't remember if I ever get a code 12, the truck has never had a vss. I tryed to mount the Camero one in the back of the speedo but I mustn't have got it right. I need to find an in the cable sensor to put in it. If I remember right,the truck has had this trouble from the start, it is on its second 305, after a 5 year rest in the weeds. The first block cracked in the lifter valley as 88s are prone to do.

I will check the voltages at the tps, that is easy enough.

Thanks

Raycr

The stumble you described may be caused by one of two things 1.)bad info to the computer or 2.)the fuel pressure regulator in the tbi unit. if the fuel pressure is fixed the cumputer will react with a pulse width correction. this is what is known (or at least shown on most scanners) as "fuel trim" and "block learn" if you have the capability check these numbers. also check if you can the o2 sensor readings with the truck in gear (tap into the wire have a buddy drive) if the reading is high and slow to react (voltage greater than .450 which indicates a stochiometric mixture 14.7:1, then you probably have fuel problems. From your original post i thought the problem occurred after the swap, but if has been a problem all along, Then the following trouble tree will probably solve your problem (and by probably i mean i'm 99% sure). START by  A.)unplugging the o2 sensor and engine coolant temp sensor completely B.)disconnecting the battery cables for approximately 10 min  (some will clear memory in 2 but some are stubborn) C.) re connect battery,leave the o2 sensor and ect unplugged, so the engine is running in "open loop" (ie running off of the base programming only)D.) start engine, if i am correct, the result will be an engine running stinking rich possibly fouling the plugs. E.) if the engine runs fine no smoke no smell, re connect the engine coolant temp sensor, and see if the problem re appears- if it does Then you have a bad ect sensor (90%of all GM's will not throw a fault code for this unless it is an open circuit-even if the reading is something truly ridiculous like -135degrees farenheight) If the ECT made no difference at all then try steps A.) thru D.)with the ECT plugged in but with the map sensor unplugged or with a different map sensor all together (if finances permit)with the map sensor unplugge the engine should start and idle but will not rev some engines will not start at all without the map , so a new or different map sensor is preferable to eliminate any guesswork.(Also check the condition of the vaccum hose for the map sensor very carefully for any problems-any leaks could cause the computer to "see"a low vaccum condition which would caus a rich mixture/ high o2 sensor voltage that the computer is more than likely trying to compensate for by going to clear flood mode) the map sensor also sends barometric pressure data to the ecu-so if this reading is off, so is everything else (i have personally seen map sensors that indicate an altitude of -400ft above sea level) as before,see if this cures it, if so, congradulations, if not then we now plug every thing but the o2 sensor in, clear the computers memory and try starting the engine. if it is still running like crap then you probably have a fuel injection problem, if this is the case, check the fuel pressure at the supply line to the tbi unit- should be 15 psi (+/- 2) if this is out of spec, correct, and see if this corrected your problem. if the fuel pressure is within spec then you have regultor/injector problems. either way, re-build the tbi unit (replace the regulator when you do)  because the excessive fuel pressure has probably done damage to the injector seals- and your problem should be solved. When you are unplugging the sensors, check the condition of the wiring very carefully. Access to a code scanner (that can read the data stream) would go a long way toward solving this problem quickly, but you can follow the steps outlined above and i am certain you will find and repair this problem            If you need any assistance or have any questions look up my e mail address in my profile and leave me a return e mail and i'll give ya my number so i can talk you thru this  or just post any problems you are having and i'll respond as soon as possible. let me know how it turns out either way!!!

Tree

 Tree, I found the stumble issue. The fuel pressure was weak, the pressure would drop to 5.5 psi under hard acc. I replaced it with an other 8153 airtec pump it still did it, but it was a bit better. I have tryed two more pumps, still the same. The tech guy at airtec said that this number should work. right now I'm running two pumps in line and it will hold pressure and run right.

Thanks for your help

Raycr

clear flood mode happens with the engine off-key on, triggered by depressing the accelerator peda to the floor three times within three seconds.

Where'd you get that info?

The ECM goes into clear flood mode whenever the TPS voltage is greater than about 4 volts & the engine speed is below 200 RPM.

OTC pamphlet that came with the scanner we had at a shop i used to work at....incedentally doing the same in a caddilac will (on the earlier efi cars) reset the oil change indicator.  

oh, almost forgot the condition you spoke of will send the computer into clear flood mode, but only temporarily. after going to clear flood mode if the condition does not improve the computer will illuminate the service engine soon light and revert to open loop operation (prom only). the method i spoke of has always done the job for me.  

oh, almost forgot the condition you spoke of will send the computer into clear flood mode, but only temporarily. after going to clear flood mode if the condition does not improve the computer will illuminate the service engine soon light and revert to open loop operation (prom only).

The condition I spoke of was CRANKING the engine with the throttle at or very near the wide open. 

1.  Clear Flood Mode is a TEMPORARY mode by design.  There wouldn't be much use for a "full time" clear flood mode.

The ECM is ALWAYS in open loop when cranking, regardless of TPS input, DTCs in memory,  or anything else.

OTC pamphlet that came with the scanner we had at a shop i used to work at....incedentally doing the same in a caddilac will (on the earlier efi cars) reset the oil change indicator.

That's strange.  According to everything I've ever read, including GM publication SD-214-A, "Throttle Body Injection," which is sitting in my lap as I type, Clear Flood mode is entered by depressing the accelerator pedal to at least the 80% or greater open position.

Quoting directly from the manual:

With the throttle wide open and cranking RPM below 600, the ECM issues injector pulses at a rate that would be equal to an air/fuel ration of 20:1.  In some applications, fuel is cut off completely, with no injector pulses from the ECM.

By the way, depressing the accel. pedal 3 times within 15 seconds KOEO will reset the oil life monitor on nearly all '96 or so & up GM cars.

By the way, depressing the accel. pedal 3 times within 15 seconds KOEO will reset the oil life monitor on nearly all '96 or so & up GM cars.

well thats a neat little tid bit to know....learn something new every day

carry on