I have a rebuilt 350 with a sniper efi on it and wonder if it would be okay to ask for advice here. I have talked to Holley and perused the usual forums and youtube videos on some of my problems and questions and have not made a lot of progress getting it dialed in or 'tuned' as they call it. My history with this forum has been positive and I would not have been able to rebuild the engine without it. Just curious as I haven't noticed much efi talk here. Mine is a quadrajet version that they make. I am going to Cruisin' the Coast this week but would like to get going on solving my headaches once we are back.
My mechanic buddy in a nearby city thinks it is burning too rich and can't explain the difficulty with hot starts. It starts perfectly on a cold start. My other friends with this same efi also complain about the weird idle patterns and a few other challenges. Thanks Steve and Jim ................
Do you have the little touchscreen hooked up so you can monitor things from the drivers seat? That thing should tell you everything you need to know. Bob
Two pump of my 750 dbl pumper and the engine starts instantly and will idle. After warmup, shut it off for an hour then reach in thru the window and turn the key and it starts right up, No gas needed, All this with the SP3. Modern technology is nice if it works as suggested.
I do and that's how the efi's computer is programmed to the engine with parameters like idle speed and so on. It runs and drives but does burn rich and has re-start problems if it dies after engine warm up. I will have more specific questions and information after we get back from CTC. Am glad this forum can be a resource as some of the efi forums haven't helped as much as I had hoped and they tend to become bogged down in technical explanations that are sometimes confusing and not readily clear [at least to me]. I often imagine younger [I am 75] and more efi savvy builders can probably grasp the efi concepts and the interplay between settings and how they affect each other .......... for example, air-fuel-ratios, idle air control, MAP, TPS, coolant temp., and on and on. I had decided pretty early in the rebuild to go with efi precisely because I have never been that good with even my simple tractor carburetors and though, maybe in error, that the computer controlled fuel injection would be "the answer" to my limited skillset. Honestly, I was a little intimidated by getting a quadrajet carburetor to function properly. I was also concerned with vapor lock as we live in Louisiana. The sniper was pretty easy to set up and get going but I ran into issues that were obviously related to fuel [or carburetion as I call it and yes I know it is fuel injection] and have been timid with making the electronic adjustments on the 'hand held' as those adjustments are very inter-related. Sorry to go on and on. More later. Thanks to all for listening! lane
The Sniper is self learning and the key data input for that is the O2 sensor. If it is running rich it could be an issue with the sensor. If it's not working properly you will see a lot of yellow and red highlights on the A/F ratio value on the sensor screen. I had an O2 sensor go bad and when the sniper can't get a reliable value it literally shuts the fuel flow off and you have to hope you can coast to a safe stopping point! There is usually some hesitation and a bunch of red alerts on the A/F value prior to that so you get some warning. If you are running stock ignition I recommend you consider getting the Hyperspark Ignition system. This is a cinch to install and once locked in place the Sniper has full control of ignition timing. I have no issues with cold starts. It took a while to learn not to pump the gas or hit the pedal after starting! Same with hot starts. In all cases, when starting wait for the sniper screen to finish booting then foot off the pedal and turn the key. Keep your foot off the gas and let it settle down. Works every time! This is the screen I have as a default for monitoring things. This is just after start up and the yellow highlight is for the coolant temp.
I would start by checking to see if your spark plugs are fouled. Add new plugs if needed. Find out how to do a reset in the computer and do that, then drive it and avoid excessive idle time. if that fails find a local EFI tuner and have them diagnose it. You essentially have a computer controlled carb, if it works properly it can be an upgrade.
Thanks Bob and Sean. New plugs. But the compromised O2 sensor makes a lot of sense because after getting the front end aligned where the shop messed up the muffler just adjacent to where the sensor was connected could have easily compromised it. Bob, I notice your IAC is at 50%. Did you go through the recommended setting of that parameter early in your setup process. My understanding is that the purpose of getting it right is that the computer/sniper will take over all the idle functions. What RPM did you set for your idle speed? .......... I can see the 947 here but they jump around a lot .......... Also, Sean I know excessive idle time is not ideal and that has been one of my problems as it has moved along. My ignition is the HEI distributor purchased from TA. Also ditto on the foot on the pedal on startup and I also learned that they can flood if I turn the key off and back on - duh! Will definitely look into the Hyperspark as my friend says it is money well spent. Thanks so much!
For the hot start problem, are there fuel curve settings for cranking? I had issues with my FAST system where it started fine cold or if I shut it down hot and started it within 5 minutes, but it had a difficult time starting after 5 minutes. I would have to wait over an hour for it to start easily when the engine was hot. Initially, the original programmer only had 1 fuel enrichment setting. You could add or subtract cranking fuel, but there was no hot or cold settings. They came out with a new programmer and now I can add or subtract cranking fuel hot, cranking fuel cold, and WOT fuel. When it was hot and wouldn't start, I sprayed the smallest shot of brake clean that I could in the throttle body and it would fire right up. The new programmer for fuel curve has 0, +/- 8 counts. I ended up setting mine at +2 for cold and + 5 for hot and now it starts great.
Thanks 73gs ............. that does seem to be an issue for me as well. My manual shows to go to 'Basic,' then 'Basic fuel,' then the 'target AFR,' Acceleration Enrichment,' and Fuel prime' but don't see anything for temperature unless the idle AF ratio or cruise AF ratio or WOT ratio are the same as to what you described. I just checked the hand held itself and it shows the same settings my manual shows. I bought my efi over two years ago and it may not have that feature. But waiting for it to cool off has been my problem from the beginning. Is it possible to install this onto the removable SIM card or whatever it is called [the removable parts on the hand held]?
Yep, unless you have port fuel injection, that’s all todays box EFI is, a barbaric TBI (Throttle Body Injection) and your one step beyond GM’s Rochester’s CCC (Computer Command Control) carburetor. Fuel injection is nice, but these companies need to be honest with the consumer and tell them after purchase “this unit may or may not run as well as a carburetor and additional parts may be needed to run properly”
I spoke to a fellow at a car show this past Sunday and he was very unhappy with Holley. He had tried to run a Sniper on a BBO in a ‘66 Cutlass, and had constant hot idle instability. Holley’s tech folks insisted it was anything and everything but the Sniper; cost him a bunch of money not to fix it. He determined that (1) the computer is waaay too slow cycling from rich to lean trying to learn, (2) never seemed to make much progress in learning, (3) is very succeptible to RFI interference and (4) doesn’t handle underhood heat well. He wound up buying an older unit (don’t know what-Pro-Jection maybe?) and it works faster and stays stable. Food for thought. Patrick
That's one reason that I went with the FAST system. The FAST has a remotely mounted ECM. I don't like the idea of having an ECM on top of the intake manifold.
I forgot to say in that post of a moment ago that something is going on with the CTS as it was reading 'Low Error' so i double checked and it wasn't unplugged and i spit on the prongs [i learned that 50 years ago for a better connection and assume everybody does it too] but it didn't improve the reading [still read Low Error]. So I just now ordered another one and another O2 sensor for good measure [per Bob's post]. Holley says in the troubleshooting section of the manual that if it reads low error it can only be unplugged, poor connection, or damaged sensor so I started my elimination process of replacing everything until something changes!!! Off to CTC but will issue an update when I get one. Thanks all
What does the coolant temperature show on the scan tool/laptop or programmer? If it is reading low, it will run rich.
