I have a '89 RS with a 350 in it (not stock) and it was running rough and someone recommended replacing the knock sensor, so I did and it runs even worse now and I kept getting code 43 (ESC Module), so I bought a new ESC module and installed it tonight, reset the computer and am still getting code 43. Does anyone have any ideas?? Im not sure but I think everything on the car was stock before they put the 350 in it, ESC module & knock sensor are for a 350.

 

Check all the connections for any poor ones to start off.

Since you bought a new ESC module it should be okay.

You could have an open or short in the circuit use a multimeter and check the wiring if all is okay.

If all of the above check out to be fine then it might be your ECM.
But since it had an engine change did they also swap the MEMCAL?

Cause Memcals are different for 305 & 350. Open the ECM up and have a look at the code on the chip and then find out if it is for a 350 or 305.

 

Ok, Should I use a multimeter to test both the knock sensor and the connector while the engine is running or when it is off? Also, what should I be looking for as in values that are returned?

Thanks.

 

You might need to extend the the length of the probes on the multimeter to be able to test the wires. Just get some wire and connect it onto the ends of the probe to give you more length and be able to test the wire ends on the cirucit you are measuring. Hope you understood what I tried to explain.

Anyway to test for a short place one probe on one wire and the other probe onto the chassi of the car or the NEGATIVE battery terminal. If you have the multimeter set to sound on short then it should buzz etc and show a value of 0 but it should buzz if it is a short. That's if you have the option on your multimeter to buzz on short otherwise it will just read 0.


If on the other hand the value is 1 then it means open circuit. I would try it with the ignition turned to ON but not started. I Don't have the wirring diagram in front of me so I can't say if you should test it with key OFF or ON. Not sure if the ESC module activates the circuit once car started. Maybe someone else knows?

I would also check the memcal if it is for a 350 or give the previous owner a call and ask when they put the 350 in did they swap the memcal.

ViperXx - I just checked the schematics and found out the following:

To test the ESC module car should be started

There should be 4 wires going into it

BROWN WIRE = GROUND
DARK BLUE = WIRE TO KNOCK SENSOR
BLACK = WIRE TO ECM PIN B7
PINK/BLACK = HOT (12v)

Let us know how it checks out.

Mike

 

Ok, thanks for the information on the wiring, will check that out later on today.. What im kinda afraid of is see, since this thing still has 350 TBI, I've bought alot of parts from Auto Zone, and they're systems list it off as 350 TPI only and they don't have a 350 TBI, they only have a 305 TBI, so when I've bought parts from them in the past they have given me things that are supposed to go on a 350 TPI and some things haven't work right. The part# of the knock sensor they sold me I belive is su154 (i'll double check it in a minute), but can someone tell me if that sensor would be incompatable with my setup? Im thinking thats why im getting a code 43, and if it is incompatable can someone tell me a compatable knock sensor I can buy?

TIA..

 

Can anyone tell me if the knock sensor from a 305 would work in a 350?? I have the knock sensor of a 350 TPI in this engine and I think its the knock sensor causing the problem, im going to replace it with the 305 sensor and see if it clears up.. Does anyone know if there is any problems with that??

 

I know some guys are using knock sensors in 350 cars that are for 305's and things are okay or so they say. But I also think that is your problem having TPI parts for a TBI car and maybe the knock sensor is the culprit. Contact the seller of the knock sensor and ask will that knock sensor work in your TBI as I am not sure to be honest.

I also know that 400Sb use a 350 Knock sensor sho I think your 305 sensor should work fine. But then again the 350 knock sensor should work also.

 

Possible.. But the reason I think the 350 knock sensor isn't working is I heard there was some sort of different communication that the 350 TPI computer uses vs. a 305 TBI computer. I just got a 305 knock sensor now, getting ready to put it in...

 

Welp, the new sensor seems to be working, no SES light, acceleration seems to be good but Im back to where I started on my original problem, which was rough idle. I know the IAC is bad, which Im going to replace in a week or so..

Can someone tell me what kind of problems you can expect from a bad IAC?

 

A Bad IAC will cause idle problems such as stalling and fluctuating RPM's.

Mine was real dirty not long ago and I cleaned it and from then on Idle was very smooth. I think your IAC just needs to be cleaned.

 

hmm, mine appears to be stuck open... Would some WD40 work? and then cleaning it? heh, that might be stupid but its the only thing I can think of besides replacing it.. I do have some carb cleaner/thottle body cleaner but im not sure what good that would do for it..

 

Spray some carby cleaner and see if that helps. Otherwise pull it out liek described in the technical articles on this web site and clean it once you have it out. It is easy to get out and clean and on the pintle there are grooves that foul up and might stop the IAC from opening and closing properly.

I'd try and clean it first usually it will solve the problem and not waste your money buying a new one when you can just clean your old one.

 

The knock sensor has a certain resistance to it depending on which computer its being used for. A TPI computer and a TBI computer are completely different, so you dont want to use a TPI knock sensor on your car. Almost all the 305 TBI sensors are the same for a 350. Next time you need something like that for your car, you can tell them you have the 305 TBI.

 

Ok, I tried cleaning it, wouldn't do anything, whole thing seemed to be locked up some how.. So I bought a new one and put it in and did exactly what the instruactions say. Car seems to be running smoother but when Im sitting at an idle it is kinda rough, when I let my foot off the gas it kinda jerks back in forth and theres a bad vibration (which was my original problem and why I've replaced so many parts)..

Here is a list of what I've replaced to fix this:
2 Fuel injectors, Fuel Filter, Fuel Pressure Regulator, Knock Sensor, Electronic Spark Control module, Idle Air Control valve, Air filter (basic maint), cleaned out throttle body completely and some timing adjustments.. and I've yet to fix the problem, and I could have replaced the whole TBI system with a brand new TPI system by now.

 

What about the rest of your ignition system, the plugs, wires, cap, and rotor?