fast efi problem

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11.2

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I recently ran into some issues with my ez efi. it started out as rough idle and stalling at idle, I reset the tps and that seemed to cure it until last weekend when I went on a road trip to the track. it stalled 3 times on the way there at highway speeds. I made 8 passes on the track with no problems then started back home and it must have stalled 10 times on the highway and 5 times when sitting at lights.
I reset the tps again yesterday and thought I had er licked but after an hour cruise it stalled twice when going through town .
any ideas, ive been on the phone with fast and they don't have any sure answers.
 
forgot to mention, on the weekend when it kept stalling I noticed that the o2 sensor would be at 00 and the computer would not learn and sooner or later it would stall
 
I have heard bad grounds are a huge gremlin in any efi retrofit system. Does your O2 have a dedicated ground lead? Especially on a ceramic coated header. Seems it should go into limp home mode if 02 sensor craps out? I have a temp sender bolted into a cast housing thats bolted to my head, it has a gasket between the housing and head and i have to run a ground wire from sender body to block, the bolts dont even ground the housing enough!
 
does not have a dedicated ground. doesn't go into limp mode and doesn't show a code.
I will try a good ground, easy enough to try.
 
Pishta is on the right track suggesting the O2 sensor and grounding. I find grounding ECU at engine is a good thing, grounding to battery -, not so good. It has to do with starting current, voltage drop in cable between battery and engine. Since many sensors including O2 and temperature are engine grounded.

The O2 sensors are much different, for wide band and narrow band. Narrow band is very high impedance, so undesired loading, or induced electrical noise can be a problem. Oil or mud on outside of sensor can make it not work. Many use wire insulation to provide oxygen reference.

Wideband sensors are more complex, and have circuit to feed sensor, and complexity in interface. If your sensor reads 00, significant problem may exist. Location of sensor is critical for reliable operation. Sensors are easily damaged, by silicones, lead in non seize, moisture...
 
im at my wits end. ive been on the phone all week with fast with no luck. ive rerouted wires, disconnected any other electronics, rewired my tack, hooked the keyed power for ecu directly to battery, set the iac, set the tps several times.... im gonna rig up a fuel pressure gauge to see if theres a problem there and if that don't work then unfortunately I'm bolting my carb back on wich is a shame, when this stuff works it works awesome but its of no use to me now.
I talked with fast about the ground at the o2 sensor and they tell me it grounds through harness.
 
How many wires on your O2 sensor? If 5-wire, it is a wideband type. Sounds like that since your computer has a linear reading for it. If 4-wire, it is a normal on/off type (or narrow-band). Either above will have a dedicated ground thru the wiring. If a 1-wire or 3-wire type, it grounds thru the exhaust pipe.

For more detail, two of the wires in the 3-wire type are for an internal electrical heater. The 4-wire type adds a dedicated ground for the signal. I think the 1-wire type were only in 1980's cars. A Megasquirt page explains all.
 
it has 4 wires.

i took a video of my handheld yesterday, i wish i new how to post it. i was cruising at about 30 mph when it stalled, after i fired it up the computer would not learn it, af ratios went up and down repeatedly and the o2 sensor stayed at 00 even went i blipped the throttle or wot. it has done this several times
 
I realize that when you talk to FAST's tech support it doesn't seem to help much. They will be pretty adamant about keeping all of the wiring as far away from everything that could cause interference and they will tend to emphasize having perfect connections on everything. When we've had problems with ours it actually did turn out to be connection issues. - Insufficient grounding or the need to reroute wires. We had not soldered all of our splices because we were having to play around with wire routing. Twice already, we've had issues that involved having to go back and solder connections.
 
i only have 2 splices, main power and ground to battey because its in the trunk. ive rerouted wires. the highest number ive seen on the rms is 08.
if the computer wont learn and randomly kills the engine, and i mean ''kills'' as if the ignition is cut, wouldn't that point towards a problem with the ecu ?
with all the wiring and adjustments ive made there is absolutley no change.
 
11.2 said:
i only have 2 splices, main power and ground to battey because its in the trunk. ive rerouted wires. the highest number ive seen on the rms is 08.
if the computer wont learn and randomly kills the engine, and i mean ''kills'' as if the ignition is cut, wouldn't that point towards a problem with the ecu ?
with all the wiring and adjustments ive made there is absolutley no change.
Click to expand...

Which distributor are you using? We originally set ours up with an MSD pro-billet that we'd locked the timing out on and added a phasable rotor. When we tried to switch to the FAST distributor we could not get the computer to program and we switched back. My son has the car a few hundred miles away and I haven't had a chance to try installing the FAST distributor again. It's been behaving with the MSD.
 
its a msd e curve. i have the fast ez efi, not the 2.0 so the only thing the dizzy does is supply tac siganal wich i understand is crutial. i originally had my tac and the fast plugged in to the dizzy and on friday the tech guy said that would be the problem for sure. i unplugged the tac, rerouted the wires and stll no change. i'm sure it's a malfunction of the fast system, this thing ran great all last summer and the first couple hundred miles this year and then started acting up.
 
I have the same exact issue with the EZEFI 1.0. If I pump the throttle too many times(like with a carb) it will go into a funk,It will stall and have to held wide open to start, run crappy, there will be no faults, its the 02 sensor on tilt. The only way to cure it for me is with a new tune, once that is done it will work without any issues. I always carry the hand held with me, dont pump the throttle to kind of show off. I have leaned it richened it and nothing helps, It works fine for eveything else. So in a way I drive it like a corolla to avoid that situation and run it as normal for all else.
 
Sounds to me like you have a low voltage problem to the fuel pump. WOT like at the track is ok. Running around town and slow cruise brings low voltage. Is your alternator or voltage regulator on its way out? Check your Fuel Pump wiring too. With the 00 on o2 sensor would make me think it's going way past lean to not even register on the gauge and stalls out.

What fuel pump are you running?
 
i ran a hose with gauge into cab and fuel pressure stays dead on 43psi

as far as the o2 sensor, when it was at 00 the af ratios change anywhere from 12 to 14 depending on throttle position.

i really appreiciate the help guys, i'm open to all ideas.

is there any way to test sensors to rule them out or if i unplug a sensor to see how it reacts. for example i unplugged the iac and it idled at 1300rpm, i went for a cruise and it stalled about 20minutes in so i assume it has nothing to do with the iac.
 
I don't know about wideband. Many of the other sensors can be substituted with resistors, temp, etc. As you discovered, IAC, etc, can be unhooked

One you cannot live without is throttle. On my Holley, once you turn off "learning" in the ECU, if the O2 goes bad or you have some other reason, you can unhook it and it still runs fairly well

No knowing what you've discussed, let's talk about ground and even power loops.

Your battery is trunk mounted? Where exactly is the power and ground mounted? On my Holley, they do mention "single point" grounding.

Also, some signals, and MSD especially warns against this, ------some signals can "crosstalk"

This is no joke with high output ignitions like MSD. That stuff is just like lightning.......a huge powerful pulse of energy, which can induce pulsed energy into other wiring. We had one guy "I could not convince" yet the answer was staring him in the face----his MSD was causing the voltage regulator to go nuts.

The other problem is some of this aftermarket "junk" may not be very well decoupled (filtered) from the power source. In the case of high- ouput ignition, this might mean that the ignition, if not well filtered ON THE power lead, can send unwanted pulse energy (EMI) right down the power lead to some OTHER component

In the case of your FAST, if THAT is not decoupled correctly, it means that it is more susceptible to EMI from other systems.

A very good example from the old days was plain old ignition interferance in AM or CB or other radios. Some of this came "down the antenna," radiated by parts of the ignition system. But in SOME cases some of it was conducted right on the 12V power lead.

This IS the reason for the capacitor (condenser) in the alternator and on the coil+ terminal in the older cars
 
my battery is grounded to frame and power going to starter, i have a ground from engine to firewall
the fast ecu is wire directly to battery and no other components are hooked to battery.
it has worked for 2000 miles this way.
on my handheld it shows a rms value, from what i understand this detects interference and if the number gets above 10 then there is a problem. so far the highest number ive seen is 8 but usually 0
 
another thing, when this thing dies it doesnt want to fire back up right away. if i sit for about 1 min then it fires right up, if i don't wait that long it will start but i have to pedal it. don't know if that helps, just want to give you guys as much info as possible
 
thanks dart 67
i tried getting on there earlier and it wouldnt connect
 
I assume this is a EZ EFI system.

From everything I have read on the FAST site these systems need to have each ground and each power wire ran direct to the battery post.

Even if each wire has to be lengthen to reach.

Also check the pins in the handheld connectors to make sure none of them are loose.

Herb
 
hmmm i just read another guy had rough idle problems and he traced it to the sparkplugs he was useing had no resistor. i changed plugs this year and used a different style then ive ever had. i'll try my old ones
 
crap, i got my hopes up but the plugs i used have resistor
 
Speaking of plugs, make sure you don't have a cracked plug or a damaged plug wire with an "open." This creates a voltage spike as the spark tries to jump the gap in the defective wire(s)

I assume? you have discussed with FAST about wire routing etc for less interferance.
 
yes, haved rerouted wires.
so last nigh i checked out fuel rails and injectors for debris, took every connection apart to inspect/clean and went for a test drive. didn't even make it 1 mile from my house and it died for good. now maybe i can find the problem
 
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