Brian McPherson's Projects

Author: Brian McPherson

  • Preparing for the wideband install

    Instead of getting a new bung drilled in the exhaust, I’ve decided to go the route of using the new wideband with the narrowband emulator and just replace the narrowband. Unfortunately, in order to do this the ‘right’ way, I have to get a new male connector to match the one on the original O2 sensor.  My research seems to indicate that GM Part #15305960 / AC Delco PT1069 is the proper replacement. Some things I’ve read suggested putting a 20 Ohm resistor on the heating lines to the original sensor so the computer doesn’t get upset, but it should be likely that I can turn that code off. I haven’t had a chance to check on that yet. I’d rather not just dump power into resistors if I don’t need to, that just seems like it’s asking for problems down the road.

    I’d also like to run wires off the stock fuse block by using some of the empty fuse sockets, but I’m not 100% sure what pins I need to order. It’s raining out currently, and it would involve popping out the existing fuse block to figure out how to do it properly since I can’t seem to find documentation anywhere online.

  • Colder plugs

    I put some cheapo autolite spark plugs in the car today because they are a step colder than the stock temp ones. It seemed to completely eliminate the hesitation I’ve been feeling when the car is already warmed up, but I haven’t gotten to put many miles on them yet. I’m really interested to see if it’ll help with the cold start issue the car has been exhibiting. I should know more tomorrow sometime. Eventually I’d like to get a better set of plugs in at this temperature, but this is all I could get my hands on today.

    If you’re interested to know what the temperature of a plug means, wikipedia has a pretty good section on plug heat range.

  • Cold start issues

    So, it’s been a bit since my last post, but a lot has happened in the past couple weeks. I’ve had a few tanks of just E85 go in so at this point it’s getting fairly close to pure E85. Cold starts have been a serious issue when the temp out is below 65F or so. It seems as though the trims aren’t being remembered on restart and I haven’t had the computer on it to know for sure. I still have the AFR set at 12.5 and I’m anticipating a lot of the problem I’m having is because of it being overly lean. There’s just no power at all and a ton of misfires  if I try to get any power above idle until the engine gets a bit to warm up.

    My wideband O2 came last week, but I haven’t had a chance to get it installed. I got a surprise call last week about this leader dog puppy I’m currently taking care of. I’m hoping to get the O2 sensor installed before the end of the month for sure. I can’t keep just guessing around trims if I want to improve the cold starting on E85.

    Future goals after getting the wideband in will be to look into making the fuel system return to the tank, and potentially getting a heated fuel rail for the really cold days.

  • A few days pass

    So, two days after having to drain the engine of water it ingested because of A2DOT breaking a water main, the car seems to be ‘happy’ again.

    I unfortunately had to put 93 octane gas into the tank last night because I still don’t know where enough E85 stations are everywhere. I need to make a map or something perhaps. I set the AFR to 12.5 to try to get a decent middle ground for either fill of E85 or 93. I’m still -20 in some of the LTFT cells where more power is made, but it’s only around -7 on average in the cells I’ve tuned the most, so there is quite a bit of work left for me to do on the VEs. I’d much rather be -20 on gas than +20 on E85, however.

    The wideband O2 sensor is supposed to come on Monday. I’m planning on getting the fuel rail tapped this weekend so I can run the fuel all out with the fuel pump. Hopefully this means I’ll have a chance of being able to tune to consistant fuel.

  • First tank impressions

    Well, now that I’ve officially ran down a full tank rather than adding to it when I feel uncomfortable about the availability of E85 on a trip, I can write down some thoughts about it. First off, yes, I saw quite a mileage decrease over 93 octane fuel. This was to be expected. I’m estimating based on how I drove on that last tank that I might have seen around 25 mpg on gas, while I got just a hair over 21 mpg on E85. This equates to a slight savings in $$ over the premium fill. I’m hoping I’ll be able to nearly eliminate the difference once I get the wideband O2 sensor so I can adjust my timing after getting it at stoich.

    As for the changes in the car’s personality? It’s much more responsive prior to the power enrich range when attempting to pass on the freeway. 65-80 in 3rd is practically instantaneous as far as one should be concerned. Cranking idle is a bit rough at first, but I’m fairly sure there’s something in the tune that I’m missing that will improve it. I’d estimate that there is a good additional 10% power under the entire curve over running 93. It’s quite significant.

  • Cobalt SS E85 conversion

    So I’ve had the thought for a few years to convert my car to run on E85 rather than 93 octane fuel. I finally got the ambition to try it out, so I ordered a set of 80#/hr injectors and installed them. I’ve been using my hptuners device to flash and calibrate the car to run more acceptably. So far it definitely seems as though there will be a possibility of increasing the power over the 93 tune.  The wideband O2 sensor I ordered from plx devices will hopefully arrive this week some time, so I’ll be able to tune off the AFR instead of the LTFTs. LTFTs have gotten me a lot closer than my calculated tune was able to do, but there’s still a whole lot of progress to do before I can consider it tuned right. I’m hoping to be able to adjust the base timing table as well, so that can be optimized for fuel efficiency and power. I’ll update with more information as I can.