pwdbychevy

Does anyone know if a knock sensor from a 5.7 TPI engine can be used on a 5.0 TPI engine and vice versa? I know they fit but will it cause any problems with the ECM (7730) . Thanks.

CaptPicardsZ28

Yes it could cause a problem. The ohms are different on the 5.7 compared to the 5.0. With speed density 7730 you need the 5.7 knock sensor.

pwdbychevy

Thanks for the reply. I have the 7730 computer w/PROM and the whole TPI unit from a 1991 Transam w/350 that I'm in the middle of installing on my 305. Do I need to use the 5.7 knock sensor or the 305 sensor since my engine is a 305?

Shaun 90 Iroc

You will need the 305 knock sensor.. also the 350 computer is used for 22lb injectors.. and the 305 has 19 lb injectors.. so the computer will try and compensate but you could run rich is my understanding.. You might want to maybe look into finding a 305 prom from somewhere or even go aftermarket.. like a SuperChip or something.

pwdbychevy

My 305 originally had a TBI on it and the TPI system comes with the 22 lb injectors. I'm assuming I will be running a little rich but we'll see what happens. I'm going to be using the 350 knock sensor since that's the only one in stock at Autozone and also the ECM and chip were from a 350 and I don't have much time left since the 305 sensor has to be special ordered.

CaptPicardsZ28

[QUOTE]Originally posted by Shaun 90 Iroc
[B]You will need the 305 knock sensor..



This is incorrect. Do a search here on the boards. DO NOT use a 5.0 on a speed density system. Use the 5.7 sensor. The ohms are different. Why am I repeating this? I switched from a 5.0 MAF to SD and I know what I am talking about.

pwdbychevy

[QUOTE]Originally posted by CaptPicardsZ28
[B]Even if the 350 setup is going on a 305? I don't mean to sound dumb but you can understand when I'm getting conflicting info. I just need to make sure before i go buy it. Thanks.

Tibo

iTrader: (15)

Go to Nappa/Car Quest/Auto-Zone, tell them you need a knock sensor for a 5.0L TPI. They will give you the correct one. Then ask them to look up the part numbers on a 5.0L and 5.7L TPI MAP system and MAF system. Compare. Come back, than say who is wrong.

pwdbychevy

The part numbers ARE different (I knew that already) but I only asked if it's ok to use the 350 knock sensor. I bought the wrong one from gmpartdirect.com because the tech article on this site gave the wrong part number. The part number given was for sensor for a V6 and now I'm stuck with it because it was special order.

Shaun 90 Iroc

I have a SD car.. sorry if the information i gave you was incorrect, but it WAS my understaning that the 305 and 350 knock sensor MAP or MAF are different.. i would like he said.. be specific on year so that the part number is correct for a SD tpi system. I know when i was purchasing a 350 knock sensor for my new 350 for my SD car.. i was different than the 305 knock sensor choices.. but Tibo could also be correct.. you are at the mercy of the knowledge and care of the parts representative at the store.. i say.. try the 350 knock sensor.. if you get a code and something is not right.. then worry about trying the 305 sensor as long as you don't come up with the same part #..

pwdbychevy

I'm going to go with the 350 sensor since the whole system came from a 350. I mean, how is the ECM going to know the difference between a 305 and 350 engine? That is a pretty good question I might ask

CaptPicardsZ28

I already explained why. They have different ohm settings. The 5.0 is 100 ohms and the 5.7 is 3.9 ohms. I believe the 92 5.7 is the right part number. Readthe attached thread and you will see that with the 7730 SD setup you need the 5.7 sensor. https://www.thirdgen.org/techbb2/sho...readid=212913. Thank you!!

CaptPicardsZ28

[QUOTE]Originally posted by Tibo
[B]Go to Nappa/Car Quest/Auto-Zone, tell them you need a knock sensor for a 5.0L TPI. They will give you the correct one.



You must have the 5.7 sensor rated for 3.9 ohms unless you are adding a resistor to the original one... Here is a copy of Mike Davis' swap from MAF to MAP. I took this from his web site.


The '730 ECM ESC circuit is looking for a 3.9K ohm resistance in the knock sensor and the '165 KS is 100.0K ohm. You can put a resistor(From Radio Shack, et al.) to bias the 100.0K ohm KS so that it appearsto the ECM as 3.9K ohm. The resistor should be between 3.8K and 4.2Kohms, and connect between the Knock Sensor wire of the ECM (GF9) andGround.

If you are building an adaptor harness like me, you can
solder this between B7 and A12 of the adaptor plug that your
harness plugs into. (assuming you are using the jumpered ESC
connector on the firewall. If you are bringing a new wire
thru the firewall, you will have to connect it and A12 with
the resistor)


If you are using the ESC connector on the firewall to bring
the KS signal in, you will have to jumper pins "C" and "E"
on the ESC harness plug. While you are building the jumper,
you can add the resistor between the jumper and pin "D"
(making it a 3-prong jumper) and your '165 KS will be properly
biased for use in the '730 ECM

pwdbychevy

[QUOTE]Originally posted by CaptPicardsZ28
[B]I measured the resistance of the V6 sensor and it read 3.9k ohms. I measured the 350 sensor and it read 3.87k ohms. I ASSume that either one will work.

Tibo

iTrader: (15)

Now that everybody likes to quote me I would like to point two things out. If the MAP system needed to use a knock sensor with different ohm ratings than wht on earth would GM make a 5.0L and a 5.7L sensor? Where is Mike Davis' swap from MAF to MAP? I have not run across that information and would like to read it. I have questions about the controls of that experiment.

Tibo

iTrader: (15)

CaptPicardsZ28, I believe that you have things mixed up and confused. The article by Mike Davis says that the 165 series ECM's knock sensor is different from the 730 series ECM. I have yet to find anywhere in that article that it compares the 5.0L sensor with the 5.7L sensor.

pwdbychevy did it right when he went out and tested the ohm resistance on his knock sensor and got the acceptable reading of 3.87. I did one better than him though. I went to car Quest, asked for and bought a 5.0L knock sensor, took it home, took an ohm reading......3.87 ohms. That's odd, because you said that the 5.0L had a 100 ohm resistance. So, I checked with a different (analog) ohm meter and got right where ...........3.87 ohms would be.

CaptPicardsZ28 now I am wondering why you thought that he had a MAF system? He is not doing a MAF to MAP conversion. He said that he had TBI. His question sounded like "are the knock sensors from the same series computer interchangable?" Which we now know that they are. They are different from different series ECMs and PROMs though. I think that you were arguing a different question than everybody else was.

CaptPicardsZ28

Guess I was missing something but my point was that the 7730 ecm is looking for 3.9 ohms not 100. I bought my wiring harness from painless when I switched to SD and they list the part number for the 100 ohm sensor thats how I know it needs 3.9 ohms. I think I ordered mine from a 92 Z28 5.7 because some of the other sensors had the same part number that Painless had listed wrong. Anyway I got mine from GM who made sure the ohms were right.

pwdbychevy

I bought a sensor from a 92 5.7 engine as well. My project will be finalized this weekend. All I have left to do is make the homemade afpr.

vernw

iTrader: (2)

OK, say you've got the 730 speed density CPU in a 91 Formula. Does the 305 and 350 use the same knock sensor for this set up?

pwdbychevy

no, they have different part numbers according to the dealer.

Tibo

iTrader: (15)

Yes. They will interchange. To quote Capt Picards Z28 the ECM (730) just needs a signal from the knock sensor of 3.87 ohms. A V6 or 305 or 350 Knock Sensor will work. 90-92 years of course. Q.E.D. It has already been discovered in this thread that they all put out 3.87 ohms.

vernw

iTrader: (2)

So now I'm really confused - the last 2 posts seem to contradict each other, don't they? They both put out the same on the 90-92's (and 91 is where my concern is), but they have different GM part numbers? Maybe I need to confirm the part numbers first....

CaptPicardsZ28

Yes

CaptPicardsZ28

Here is the link to his web page. http://www.eecis.udel.edu/~davis/z28/

Abird4u2nv1

iTrader: (-1)

Here let me help guys so this will get settled.

Just go to your local parts stor and tell them what you need, its that simple. If its a SD system, tell them you need a knock sensor for a 91-92 305 if thats what you have. If its a 350, tell them 91-92 350. If its MAF system, tell them knck sensor for an 89 305 or 350 dpending on motor.

Don't buy a knock sensor for a different size engine. Buy one for the year of your TPI and motor size.

pwdbychevy

I thought this issue had died a long time ago but to answer my own question, I've been using the 350 sensor on my 305 since February and have had no problems at all. Knock count is normal.

DSLDUDE2001

I didnt read most of this thread, but i just did a TPI swap on my L03. If you have a memcal for a 350, buy a 350 knock sensor. If you have a 305 memcal, buy the 305 KS. The KS calibration circutry (or whatever you want to call it) is on one half of the memcal, and the prom is the other half. Also, get into prom burning. In order to tune that setup properly, you will need to datalog and changeup your injector constant and fuel tables.

DSLDUDE2001

oops, i should have read the thread....

to sum things up: a 350 KS will work on a 305 if you have the appropriate memcal.

pwdbychevy

I'm using the 350 knock sensor with a modified 305 memcal (SUPER AUJP CCP spark and VE tables) and the car runs great.

Locherle

[QUOTE=CaptPicardsZ28;1681705]Hey,

I have code 43, last owner changed ecm and (Replacement AC Delco) and Knocksensor.
ESC is in Memcal included. How tp find out that they installed the correct sensor?
5.0l TPI '91 “F“.

Thanks

Danny

Tuned Performance

iTrader: (92)

It will ohm out at 3.9k