Well, I think I have finally figured out what was causing the car to go into a lean condition. I have done so many mods on this car to get it ready for the Supercharger that I can't figure all the problems that are arising quickly. I did change the system over from a 1 wire 02 sensor to a 3 wire heated O2 sensor. I figured it would help since the exhaust was jet coated from the headers to the Empty cat. Car would run for about 6 minutes with BLM's around 108 then skyrocket after 6 minutes to 160 and then the DTC errors would occur in Datamaster. Tonight I put a new stock 1 wire in and the car stayed running over 20 minutes with BLM's around 110-112. Never did exceed 128. Does anyone have a guess as to why that problem occured on the 3 wire.

Now I have to figure out the knock counts.

I was told since I switched from a 165 MAF ECM to a 730 S/D in preparation to goto a 749 ECM that I should wire the knock sensor directly to the ECM and bypass the ESC. Now the system is backfiring and giving me excessive knock counts on Datamaster and my Span-On MT-2500.

Should I pull time from the Eprom to account for the knock counts or put the ESC back in give it a try?

 

Did you change the knock sensor? The 730 takes a different knock sensor. I think I had that problem once, IIRC, the parts store sold me a TBI sensor the same sensor as 165 ecm when I did a swap once and I think I had excessive knock counts. Leave the ESC module bypassed its all done in the 730 ecm.

I dont know on the 3wire O2 though, thats wierd .

 

Tonight, I was curious if a compression check would tell me anything about the valves being lazy or bent. All cylinders were 148-150. Well, that didn't take me anywhere. So, I put the new spark plugs in and gave that a whirl. Car started right up and stayed again in Rich mode which is fine with me. At least it isn't going into lean again. I will use VE Master and reburn my prom to get my BLM's to 128 once I figure out where these knock counts are coming from. Here is another scenerio

Car is a 87 IROC that used to have a 305 TPI and MAF using a 165 ECM

I put a 92 rebuilt Engine in. Swapped the MAF for S/D and used a 730 ECM
I also changed the 305 knock sensor and bought a 350 sensor.

I am planning in the near future on using the 749 ECM with 2 bar map which I already have in my garage.

The instructions said to remove the wires on the ESC which go to the knock sensor and ECM and splice them togethor. But is that strictly for the 749 ECM or the 730 also.?

I did splice them togethor. Now I am banging out knock counts like crazy.

1. Should I wire the ESC back into the harness or leave it as the 730 is supposed to control timing.
2. What about the distrib. I am still using the 305 TPI distib with the 730/749. Should I get a new distrib and or distrib module or leave it alone? I have the distrib for the 92 vette where the engine originally came from. The ECM was from a 1998 Donor Car.

 

Make sure your knock sensor is for a TPI 730 engine and not a TBI 350. They're different.

 

The knock sensor is for a 350 engine. I had ordered another one just to make sure. What causes the ECM to retard the engine? I know if it picks up knock counts it will pull timing. But what if the initial spark tables are not right. Where on the $58 spark tables can you check the spark tables?

 

Did you jumper the knock sensor so it goes directly into the ECM and not via the ESC module?

I unplugged my ESC module and made a small jumper wire and jumpered 2 pins on the ESC module and taped it up so it does not fall out. The connector stays unplugged. This way the wire from the Knock sensor goes right to the ECM.

I am not sure which ESC pins to jumper but you can test it with a multimter to find which wire is coming from the knock sensor and which wire leads to the ECM and those are the wires you jumper.

You also changed memcals for the 730 ecm right?

 

I have bypassed the ESC and put a AUJP memcal in. I have been reading quite a bit tonight on pulling timing out to help retard the timing. But, Should I tune in Open Loop so the computer don't interfere? There is alot of references from a Moderator named Lumpy and Traixon about TPIS and pump shots and timing. That is maybe the way I am going to start looking. I have seen there are quite a few people that are having the same troubles with the miniram. I have even seen some sell it and get a super-ram and they say the troubles disappear. I am determined to get this working. Then once it works right I will have to start all over again once the Supercharger is on there. Plus I have to repin again to the 749. <<< SIGH >>> Oh what to takes to beat the fast and the furious.

Let me know if you have any any more ideas.

 

Do not try to tune in open loop without a WBO2 sensor.

Did you double check the wiring with an ohm meter from the knock sensor plug (disconnected) to the ECM knock pin (disconnected)?
Did you double check all wiring at the ECM connectors?
Ohm the knock sensor and verify that it is a 3.9 Kohm knock sensor.

Is it getting knock counts while idling? Is the knock present at constant RPM? Or is it just when you change throttle position (AE / pump shot)?

Yes, that is good you didn't put the S/C on it yet. What is the intake & cam?

EDIT: FWIW, I had to increase the AUJP mask AE when using an LT1 intake (like mini-ram) and 216* @ .050" cam. It did not cause any knock, but there was a stumble when getting into the throttle. I had to decrease the $58 BBZB AE with the same setup.

 

Well, I was reading what grumpy and others have wrote about the knock. I have a TPIS miniram.. Looks like there are many others out there that are having very simular problems. At idle I was getting constant knock counts like 2 seconds. At higher RPM's they would like like 50+ knocks per second. I was advised to give it plenty more fuel which I did only around the 800 - 1000 rpm range and the knock counts almost came to a complete stop. I know the TPIS mini-ram likes alot more fuel now. I will have to start ramping the timing in and out faster also. I honestly think now that I would be wasting my time with the 730 ecm and getting a prefect tune if I plan on going to the 749 very shortly anyway.

I have to follow the advise of Grumpy and Fuel & Timing



I have rechecked the wiring to the ECM like 10 times and can't find any problems. I will keep you updated on the swap. Everything is in the garage and on hand and will let you know how it turns out.

 

If using saturated injectors, keep the 730 ECM.
If using peak and hold injectors, use the 749 ECM.
You gain nothing by using the 749 ECM with saturated injectors.

 

I am running Ford #42 lb injectors. How do I know which is which?

 

Post the Ford part number or use google to find out if they are saturated injectors (12 - 16 ohms). Or you could just put an ohm meter on them and measure the resistance yourself. What ever is easier for you.
Watch out for the $8D to $58 swap sticky post.......some of the wiring changes that it says are wrong and some do not need to be done.