superirocz

iTrader: (5)

having a weird issue with my distributor. I have a 89 iroc with a sbc with a FAST ecm. I replaced my old holley stealth ram intake last week with a new single plane converted to efi with a accufab 90mm tb. I dropped in the distributor and it starts for justa a second or two and shuts off. When I turn the distributor I hear my fuel pump kick on and off like something is grounding out. Everytime I twist the distributor it grounds out. I upluged the 2 prong connector that goes to the ignition module and to the coil and the it does not do it. I didn't have my Fluke with me and my electrical skills are pretty bad anyway. The ignition is just your standard sbc setup with the ignition module in the distributor. I have checked visiauly the wires and can't find any issues close to the distributor. Is it possible the pick up coil in the distributor is bad. I hate it when I make a change justa simple intake swap and the car develops a mysterious electrical issue.

Every time I twist the distributor it kicks the fuel pump on.

junkcltr

iTrader: (1)

That is the problem with aftermarket ECMs. You don't know how well they are coded.

It could be just the ECM seeing the distributor reference pulse (DRP) when you twist the distributor (and also cause a plug to fire). That is what it sounds like to me. What is the problem you are trying to solve?

superirocz

iTrader: (5)

I don't think the ecm has anything to do with it.
The problem is I changed my intake and dropped the distributor back in and was going to start it up and set my timing. The car will fire and run smooth for just a couiple seconds and shuts of. The car was running fine before I swapped intakes.

IROC-You

ok, i dont know about the FAST system, but i know the Megasquirt will turn the fuel pump on, if it does not see an ignition pulse within 2 seconds it will cut the fuel pump off, this is a safety feature. I had this same problem and it was because i spliced the wrong wire for ignition pulse.

What i would do is crank over your engine and watch your laptop for the RPM signal, if it suddenly cuts off, this is probably why.

junkcltr

iTrader: (1)

Every ECM I have seen turns on the fuel pump for the initial squirt. Maybe his is different or wired incorrectly.

fbodyguy86

my factory setup will do that to as it is sending a signal through the oil pressure sending unit which will allow the fuel pump to run if the motor loses oil pressure the fuel pump turns off to save the motor

junkcltr

iTrader: (1)

A factory ECM turns on the pump for the initial squirt. The oil pressure switch should close once the engine is spinning and supply the pump after that.

As for the car starting and running for a few seconds. That is a problem. If you wired the car properly then it is as simple as you need to connect the plug on the oil pressure switch again. It sounds like you forgot to connect it......that is why it stalls after the ECM fuel pump squirt.

IROC-You

Try bypassing the oil pressure switch.

I did this on mine, as i heard the switch will go bad and leave you stranded on the side of the road.

junkcltr

iTrader: (1)

The oil switch also cuts the fuel when the engine stalls in an accident. It is more unsafe without it. Pressurized gas fires burn things quickly including others that are part of the crash and do have their oil pressure switch installed.

superirocz

iTrader: (5)

I don't have a oil presure switch. The factory ecm and wiring is all out of the car. I didn't rewire anything. The ecm prime the pump when the key is on the on position. Its after the ignition is on and you turn the distributor from side to side it kicks the pump on like something is grounding out. All I did was swap intakes
Thanks for the tips


Where and what is this oil presure saftety switch??

junkcltr

iTrader: (1)

The oil switch is either right under the distributor or above the oil filter. Usually under the distributor (the top oil port at the back of the block). The black connector has two heavy wires. Not sure what you have for a harness with the non-stock ECM.

EDIT: Not sure how you wired things. Could it simply be bad ground wiring? How did you wire the fuel pump relay if it is not wired like the stock one?

superirocz

iTrader: (5)

the oil presure sending unit under the distributor in the block has been out of the car for 3 years. If there is some other switch its never been in my car?

JAYDUBB

Its right above the oil filter pad on the driver side of the block. As mentioned before, it the switch closes when there is oil pressure. This energizes the fuel pump relay and sends 12 volts to the fuel pump. If this is disconnected, the fuel pump will not run. This is works on the FACTORY ECM though. Not sure about the FAST ECM though...

superirocz

iTrader: (5)

I don't have that switch. The FAST does not have any provision for a oil saafety switch. I have had the motor out of the car 4 times in the last 3 years and never pluged or unpluged any oil switch. I thought I new all the parts of an 89 iroc but guess not. I plan on taking another look tommorow.

zz4z28

Hey Matt-
it's marc, have someone help you and find out if its losing spark when it dies or fuel pressure. I wonder if somehow the program in the FAST has changed so it runs with the afterstart settings but then after two seconds goes back to the base map and the base map has changed somehow.

mine did that one time I lost an entire ve map while doing dyno runs it ran the first pass and then we tried to fire it the second time and nothing happened

superirocz

iTrader: (5)

Thanks Marc, I just got that elbow yesterday and it looks awesome. Tommorow night I will figure it out and look at my file. I was going to check it out tonight but sprung a leak in my house.

superirocz

iTrader: (5)

I worked on the car today. The turning distributor is turning the fuel pump on thats normal, my bad. The car though almost fires and runs smooth for just a second or 3. I was watching the my laptop and my rpm signal is read and turns yellow when she starts to fire and goes red again when she dies like the rpm signal is coming and going. At this point I have changed the ignition module and also re downloaded a new ecm file. The only thing I can guess is the pick up coil in the dizzy is bad. I have an extra one and will be swaping it in tonight. I also bypased the mallory ignition box and msd coil with the factory coil and still no go. If the distributor pick up is the only thing left I hope.

IROC-You

It could be interference.

Is your RPM signal wire shielded? If it is not, try routing it away from your spark plug wires. If this doesnt help you could also grab some aluminum foil and then wrap your wire with it until you get a suffecient distance away from the spark plug wires. If it runs then you will need to replace that wire with a shielded one.

The alum foil trick should be faily easy, alot easier than replacing the pick up coil, so thats what i would try first.

superirocz

iTrader: (5)

The wires to the ignition module are in a loom. I will give the a try

superirocz

iTrader: (5)

UPDATE
I just pulled the distributot out and put my old used one in and now the ecm is geting no 0 rpm signal at all. I pull it and slide my original back in and it has a signal in yellow when it tries to start and red when it dies. So How can I test my one that is atleast working for a few seconds?

superirocz

iTrader: (5)

pu coil is good, 772 ohm

IROC-You

Well if you get a tach signal at all, i would think that your wiring should be good enough to get it to run.

I am not familiar with the FAST system, but to me it sounds like your initial 2-3 sec runtime could be your afterstart enrichment. Once this enrichment dies off, the engine becomes too lean and cuts out.

What i would do is richen up the lower part of the fuel map below 2000rpm. It should run even if its very rich. Once you get it actually running, you can lean it out to the desired level.
----------
Also, do you have your tach signal wired into pin "R" in this image?



Its the purple wire, not the white.
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Also, can you confirm that you are getting an actual RPM signal? I dont care if the screen turns yellow or red.

While cranking, you should be showing over 250rpm's. You need to look for an actual Realtime display of the RPM the FAST ECU is seeing.

If you are getting an RPM signal, i think the issue like i said before is going to be fuel related.

superirocz

iTrader: (5)

On the FAST it goes up to about 400-700 rpm so its getting a signal and yes I can see the numbers as its cranking and starting the car up. I went ahead and brought the car up to tdc and dropped the dizzy back in, no dice. What I don't understand is the car ran fine for the last year and I pull the HSR intake and swap in a single plane with a 90mm accufab TB all in a weeks time. The car should run fine it may need minor tweaking but something else in screwed. It also after it fires for 2-3 seconds the tack dives to 0 likesomeone pulled the power wire to the ecu and thats why the car won't stay running. Its as if the ecu is shutting the car of. I will call FAST tommorow but there not much help.

I bought the ford TPS with the GM connector from precsion turbo and hooked up the same gm iac sensor to the 90mm tb.

I'am so pissed all i want to do is part this thing out.

IROC-You

Ok, when you say the engine cuts out and the rpm drops to zero... does the rpm drop to 0 and THEN the engine dies? Or does the engine die first and then the rpm drop to 0? I know this all happens very quickly, so try to pay attention.

If the rpm signal drops to 0 FIRST, and then the engine cuts off, its definatley an ignition problem, or at least an ignition signal problem to the ecu.

If the engine dies first and then the ign drops to 0, well then this is normal

What is controlling your spark? What kind of Dizzy do you have? Is the FAST unit able to control spark?

If you have the stock ECM controlling spark... well then it could be anyone of multiple posibilities. What i would do is either use the FAST to control spark using direct coil control, this will bypass the GM ignition module.

If the FAST cannot control spark, i would try to get an old vacuum advance non-computer controlled dizzy. This will eliminate the possibility of any sort of electronic malfunction causing the no spark situation and let you focus on fuel only.

superirocz

iTrader: (5)

I think it was just dying and then the signal went away as normal. I will double check that tonight. I have the factory dizzy with a factory style accel ignition module controling spark and sending the info to the FAST ecu. I did pick up a new ignition module today and will give that a try. The map sensor is getting a good vacum point. I will see if anyone has a old vacum dizzy i can borrow

askulte

Time to get the scope out. The ignition module in the distributor takes the AC wave from the reluctor wheel (P & N), and converts it to a square wave on the REF terminal on the HEI module. This goes to the FAST ECU, which adds enough of a delay to be an advanced spark for the next cylinder, and then sends a square pulse back to the ignition module's EST terminal. The module then fires the coil through the "C" terminal. The HEI module also needs 2-8V on the bypass line when the engine is running, otherwise it goes into limp home mode, ignores the EST pulse, and runs at 6 degrees BTDC. Check fuel pressure when running, or at least see if there is fuel pressure after the engine shuts off. The rails should stay pressurized for quite a while. I just re-wired the Accel 300+ with my DFI 6 last night, so this is fresh in my mind...

superirocz

iTrader: (5)

I tried the new ignition module and fires up and pops and backfires loud. The car is at my brothers shop and they think the timing is of or 180 out. ASkulte electronics are not my strong pointe i wish I had someone to show me how hands on.
I pulled the dizzy last night and put a rag in the #1 piston and turned the motor until it poped out and it was an inch from 0 degrees so i turned it to zero and then droped the dizzy back in and positioned the cap so #1 plug wire was just over the pointer in the dizzy. Is it posible for the rag to pop out under presure and the piston not be at the top of the stroke?

askulte

Put a rag in the piston? I'm confused now... The old mantra: suck squeeze bang blow. To verify TDC, remove the spark plug on #1, and you'll feel the pressure as the piston starts to compress the air (and won't feel it 360 deg later). Or did you mean that you've got the rag plugged into the #1 spark plug hole? If it bucks and pops, have someone keep the engine running, and you try rotating the distributor one way or the other until it's happy. Better way is to take a timing light, and see where it lights up. Leave the bypass line disconnected on the distributor, and you should set the distributor at 6 degrees, I believe.

superirocz

iTrader: (5)

I put a rag in where the spark plug goes and it shoots it out when the piston comes up to TDC.

superirocz

iTrader: (5)

Well tommorow night i will drop the dizzy back for the 3rd time. I don't think it will change anything but its the only thing left for me to do. I don't what to do next the closest shop is a 4 hour drive that even works on cars like these.

zz4z28

matt-
Just to be sure once the rag pops out make sure the crank is at 0 degrees on the balancer and then take the cap off the dist.
and put it in and make sure the rotor is pointing towards the #1 spark plug hole. once thats in put it back together with the dist loose and have someone fire it and turn the cap either way till it will run if it will.

kinda sounds like it might be 180 out seeoing as how you didn't change anything else it kinda sounda like that could be it.

with my past experience if the module was bad it just wouldn't fire and if my wiring was bad the same thing happened it would not fire!

hopefully it is something simple. it usually is when this kinda thing happens.
I cant imagine pulling the dist out would cause it to have component failure.

also make sure you try to keep it running by hand or foot cause it might be iac and also watch for tps signal. turn the key on and watch the parameters of the tps at closed and then open.
it could be tps related?

good luck, wish I was close enough to come by and help!

90Formula-X-F

OHM THE INJECTORS !!!

All injectors should be with'n a couple of clicks of each other. That means that if most of them are 14.5 then the max and min are 14.3 to 14.7. Don't believe that anything else is acceptable. If G.M. or any aftermarket gives you a spec of say 12 --16 whatever, it's a spec that changes under heat and conditions and they could fall in that area but what you don't read is in that spectrum when tested they should all be simular if not exact. Find the one thats either shorted or close to it and unplug it and I bet she runs. You really don't even need to know the spec. you'll have a bunch that are almost exect and one that's way off and maybe more that are out of range. If it's not within a couple of clicks (Milli ohms) either way of the average its a problem. Start ohm'n you'll find it. Your gonna find one thats 2.0 or something maybe closer to zero which is dead shorted. pop of the connector.

I'm a G.M. drivability/master tech with over 30 years experiance in a massivly buisy market. The only reason I'm telling you this is people are gonna start ******* what I say but it's reality and to think not and run around with a few sour injectors makes them a car length behind the person with the right stuff... Focus on it !

Good Luck

superirocz

iTrader: (5)

I will mess with it tonight or tommorow we just got are first nor eastern in a few years. I will check the injectors to.

superirocz

iTrader: (5)

I took my distributor apart and the pu coil looks very rough. Although with my probe it reads 772 ohms it looks like it may be shorting out. Here are some pics. The white fuzy stuff looks like paper shredings. My camera is a bit blury that close.

superirocz

iTrader: (5)

a much better pic


Just to be sure the green wire on the pu coil goes to the P prong on the ignition module correct

FSTFBDY

iTrader: (33)

anybody local to you have another distrib to try?

id check yor Fuel PSi as mentioned above. Ya you can hear it kick on for a sec. but it could be on its way out and down on fuel PSI.

Sounds to me like something small and just getting over looked. (ive been there done that many times) A pinched dist. wire had me running circles before.

Like I said on the PH. If your new MAP and other things don't work I can always make the drive and come give you a hand. 2 people are better then 1 tryin to figure things out.

superirocz

iTrader: (5)

No dizzy, nobody is in to cars around here there either a ******* or stuck up profesor type. Well I can't get a map sensor they are special order. How can I see if my iac sensor is any good?

Today the car won't even run it just bucks and backfires real bad. Last night it would atleast run for a few seconds. Who wants this heap of ****??

FSTFBDY

iTrader: (33)

mmm, can't you test a MAP sensor with a meter also?Should change reading with change in vacuume. Got a hand help vacume pump? like one for bleeting brakes?

I dono with a FAST how to trip the IAC to reset it. Might be just like a stock ecu. do you have a ALDL port still? You should be able ot hear the IAC Stepper motor when you reset it.

I'll take the heap if its free...lol.. J/K I know its frustrating but stick with it. You have alot of good pars tossed in that car now its just workin the bugs out.

like you said whats sh*ty is all you did was swap intakes.... mmmmm

superirocz

iTrader: (5)

I don't have a vacum pump. There is no ALDL port on the FAST. I will try to see if I can hear the iac motor

techno101

So did you ever verify that it was not 180 out??

superirocz

iTrader: (5)

yes I brought the car up to TDC and then stuck a small rod in the spark plug hole and you could feel the piston at the very top of the bore.

techno101

did you take off the valve cover to verify you're not on the wrong stroke? #1 in relation to #6 I think?

FSTFBDY

iTrader: (33)

You dont have to pull a valve cover off. like Andrew said above....

I always stick my thumb over the #1 hole and wait for the blow. Then check the timing marks.. Drop the dizzy in with rotor pointing to the #1 hole and you should be good to go.

superirocz

iTrader: (5)

I put a rag in the plug hole and it pops out anf just for extra measure I put a small rod in the hole to feel for the piston as its at the very top and you can feel the piston start to drop back down. Heading back to the shop tonight to look for something.

Blown87

iTrader: (1)

I hate to repeat what others have already said, but it really sounds like a timing issue. It may be possible that the rag is popping out of the cylinder during the exhaust stroke. At this point I would recommed that you remove the drivers side valve cover and verify that the #1 intake and exhaust valves are closed when approching DTC. Then intall the distributor. At least once you do this you can put the timing issue to rest.
By replacing the intake the only thing you should have disturbed is the timing, and granted you will need to tune the engine for the new intake, but the old program should run the new setup.
Good luck and try not to get too fustrated. Keep us posted.

superirocz

iTrader: (5)

The one factory GM connector that goes on the coil is in bad shape. The one wire is dryrotted and the other was 80% cut in half right at the connector. This has got to be the issue. I just need to get a connector tommorow from the junkyard.

techno101

Is it the black connector?? I had a similar problem when I swapped engines. My black connector was cracked and I had the wire going over the top of the dizzy cap too. I replaced the connector and lengthend the wires about 6 inches. Enough to run the wires around the back of the dizzy. Car ran awesome afterwards.

superirocz

iTrader: (5)

its the grey connector it slides onto the black connector and they then plug into the factory coil or in my cas my adapter connector that goes to my msd coil.

techno101

thats got to be it, I'd spring for a new connector. Probably about $10 at Autozone or some place like that.

superirocz

iTrader: (5)

UPDATE

I found a GM connector so I whip that on and still no go (big surprise). Well that was going to be an issue real soon there was only a few starnds of wire holding that one on. I pulled a spark plug and those babies are black and now I wonder if its fouled them all. It almost wants to run but no go. The plugs are NGK BKR7E there not that old but I have been cranking on this bitch for 3 weekends like a freaking monkey

Tommorow night I will wip in a new set of plugs.