First time starting help

blown87 · Post by **blown87** » Wed Jan 25, 2006 9:38 am

I have installed my megasquirt on my 305 TPI/ Supercharged chevy. I have piggybacked it so that I can learn how to tune fuel before tuning spark. The engine starts, runs for about 10-15 seconds, floods, and stalls. Now I know that at my idle pulse width is high (about 14 ms) and I need to tune required fuel and warm up enrichment, but I noticed in my data log that my MAT and CLT are at -4 F. The car is in a garage and the ambient air temp is about 40 F. My concerene before I attempt to start tuning, is that I am in the wrong enrichment cell causing the flooding condition. These are GM sensors so I don't think that I have to tune using the thermistor porgram. I have included my datalog if it helps. Can anyone give me some direction? Thanks. I am using MS II V3.o board with code 2.33.

blown87 · Post by **blown87** » Thu Jan 26, 2006 6:02 am

I now suspect that the Megasquirt is misreading the coolant temp sensor. I wired the IAT and CLT sensors directly to the Megasquirt and the readings changed. The IAT is correct now, but the coolant sensor is reading 7 F. The coolant temp is actually 40 F.
I have checked resistance through the wiring to MS and am getting 6.5K ohms resistance, which tells me the coolant temp sensor and wiring are ok. So I opened up the MS and checked R7 & R8. Both readings are correct (2.5K & 2.2K respectively). I have checked C6 & C7, they are installed in the correct positions with good solder joints. Can I check the actual capacitance while in the board? I have tried (using jumper wires from the meter to the capacitors) but am getting an out of limit reading on my meter. If one of the capacitors are bad will it skew my coolant temp reading? I ran the car for about 10 minutes and my temp guage was reading right at 200 F, but MS was reading 92F. As I stated before, I want to make sure that my coolant temp readings are correct so that the warm up enrichment is correct.

Fastest95PGT · Post by **Fastest95PGT** » Fri Jan 27, 2006 5:54 am

Are you sure you don't mean -40F? I noticed that when I unplugged my IAT once, it went to -40F. I was surprised because I expected it to go to 170F (failed sensor temp) but it did not.

Also, since you're running in parallel with your stock ECU, are you sharing it's sensors too? If so, do you have R4 and R7 installed on the MS board? If so, I think they are likely the cause for your readings to be wrong.