OK, brand new to the board and let me tell you, it's LOADED with great info!!

Here's a little background:

I'm a Jeep guy and this motor is in it.

I have a 1991 9C1 motor that I tore apart, re-ringed and put new bearings in. All the internals were in good shape, so I just put everything back together. I have this odd problem with surging from 1200 - 2000 RPM though. When I have the Jeep just idling in the driveway and hit the throttle, the injectors begin to "pulse" with about a half second "no spray" condition in the RPM range I described above. Once past that, the conical pattern is more steady and it runs better, not great, but better. I drove it yesterday and it reacts exactly the same on the road. Idle is great.

I have brand new:

Wiring harness (Howell)
Fuel pump
Plugs
Wires
Dist cap
Rotor
Pick up coil
Knock sensor
ESC module
Fuel lines
Fuel filter

I have also tested every other sensor under the hood and they all check out OK. Cleaned the IAC with instructions from this site. Checked all plug wires, all still great. Ignition module checks out fine. Haven't checked fuel pressure yet, but wouldn't it run crappy ALL the time if that was down?

I am also getting a code 43, hence the reason I have new knock and ESC. Funny thing is, it doesn't set hard enough to kick the SES light on, just when I check the codes after shutting down, it's there. I have cleared it MANY times, yet it returns.

I also have a custom burned chip from tbichips.com for a 5.7 truck with manual, since that's my basic setup.

Exhaust is a 2" into 3" single to a 2 chamber Flowmaster.

I am also running a '7747 computer.

Timing is dead on at 0* with EST line disconnected.

Any ideas why I'm getting this "pulsing" or "pausing" of the injectors?

And would eliminating the knock test get rid of my code 43 error?

Please help, tired of throwing money at this stupid thing!!

P.S. Laptop should be here today or tomorrow and I'm gonna run WINALDL with home built cable for more info.

Good idea. I think you will find the error is in the chip. 1 burn is not enough.

Just a WAG but it sounds like the ecm may be going async because of the pulsewidth gettting too short. The ecm may skip injections entirely in async fuel and carry them over to a later time. The up and down afrs will effect how the motor runs.

Your TPS is wired backwards. Try this: find the little tab on the TPS sensor that contacts the throttle body linkage, move just the tab. If the fuel cuts off then switch the two outer wires on the TPS sensor (if true thank JP for this tidbit of information. . . ).

RBob.

Well, I pretty much verified last night that it isn't the chip. I had the stocker laying on the workbench, threw it in for s's and g's. Nope, same thing.

OK, as far as the ECM going async, how the frig do I fix that?!!?

I'll check the TPS tonight, however, I had previously thought it might be bad, so I put my volt meter on the input at the ECM connector and watched the voltage as I hit the throttle. It rises steadily from .48 volts to about 3.5 at full throttle. And when the RPM's are fluctuating, the TPS voltage is steady as a rock.

Ken

UPDATE:

Well, sort of. I have the laptop, built my cable and downloaded WINALDL, but now I have to drop $$ on a USB to RS232 connector, the new Dell has nothing but USB.

Been doing a lot more searching on here as well.

Another question: I replaced the pickup coil and cleaned the corrosion off the pickup pole piece and the pole itself, however, I wasn't really paying attention to check the air gap or the magnetic-ness of the pole piece. After extensive reading here, I see that a weak signal from the pickup coil to the ECM can result in a low output on the other side. So, could this possibly be my problem?

I am also getting a jumping/bouncing on my Autometer tach. I can be cruising down the road, 4th gear, about 40 MPH and the tach is reading 4000 RPM. I know that's not right, it should be about half that. Other times, it's just bouncing all over the damn place even though the motor isn't. Wondering if this could be related to the reference pulse as well.

When I get the surging, and I floor it, it almost feels as if the motor has loaded up, even though it's not getting the pulses of fuel, it runs as though it has gotten too much until it clears itself out.

This is driving me INSANE!!!

MORE TESTING:

Here's something intriguing, I was testing this some more today. I found that when I unplug the EST bypass wire, I get no surging whatsoever, engine runs smooth. When I plug it back in, turn the motor off and restart, surging returns.

I checked the module, it reads 253 ohms or so at ckt 423, reading goes up with a test light connected to ckt 424 and 12V to about 5600 ohms. According to the manual, the module should be good then.

I have tried 2 other ECM's and they both run the same. The only way I have found to "cure" the surge is by unplugging the EST bypass. As far as I can tell, the only two parts in this system are the ignition module and ECM. So, even though the module SEEMS to check out, could it still be bad? I can't imagine it's all 3 of the ECM's I have tried.

Sounds like the ecm is retarding your timing in this range. with the EST bypassed the ecm doesn't control timeing and the distributor locks timing. When you get your aldl cable up and running I bet your going to find your getting knock in this rpm range. This could be caused by a number of things, including the exhaust hitting the frame. You might try disconnecting the knock sensor and see what happens. You'll get a code, but it should let you know if thats your problem.

As I suspected, it was a really stupid problem.

As I mentioned, this motor is in a Jeep. For the most part, I replaced everything under the hood, EXCEPT, 2 wires coming from the igniton switch for ignition "on" and "start". Well, Jeep, in it's infinite wisdom, made the "on" wire some kind of a resistor wire. With ignition "on", it read 12.8V, as soon as I started it, it dropped to 10.5V. Well, the coil and ECM do not like anything less than 12V, this I have learned.

I pulled a new 14 guage wire thru the harness, fired her up and she runs GREAT!!! No more surging, no more hesitation and (I haven't checked yet) but I believe the code 43 will probably disappear as well.

So this 4 foot section of wire cost me a couple hundred in sensors and whatnot, another $900 for a laptop (that I have yet to get to work) and countless headaches.

The one good thing - I know this motor and system inside and out now. Should be able to diagnose damn near anything.

I think the thirdgens are the same way. The wire coming off off the ingnition is a resistance type wire. Glad to hear you fixed it.