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spfi swap wont start now


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About a week ago I did the spfi swap on me ea81. Everything was off of an 88 dl with a manual tranny. I also have an extra 93 ecu as well. I swapped my tranny out for a different one on tuesday. Seems after I did the swap it was getting harder to start. No I didn't mess with any electrical connections other than the tranny harness connector.

 

When I first got it going after the spfi swap it would barely rotate and fire right up, faster than some new cars. After the tranny swap though It would rotate a few times then fire as I let off of my push start button. It kept taking longer to fire and would do the same thing, as soon as I would let off the button it would fire. I have my starter push button hooked up to a relay the start signal ecu wire (light green one) is hooked up to the push button. Now it won't start at all.. it has fuel, I know that. The fuel pump runs when you attempt to start it and the throttle blade is wet when you take the intake off.

 

I've checked:

MAF- good voltage. Good ground continuity. Signal wire voltage changes when you blow into it.

coil- battery voltage on both sides of the coil. The bracket is grounded good and the transformer deal has voltage to I think the black wire. Other wire has ground continuity.

air control valve- has voltage to black/white wire. Coninuity to ecu plug for ground signal wire. I also cleaned it when I turned it around for the swap.

Rotor screw is still in and rotor is tight.

Cap is good.

spark plugs are a couple weeks old.

No codes except when green connectors are plugged in. Which is 34 for the egr. I just got resistors to put in place of it.

 

It fired up this morning after some cranking then gradually went to nothing. What am I missing? From what I've researched the ecu needs crank angle signal to keep fuel pump running. If you give power to the start signal wire by itself you can here the fuel pump pulse. Fuses are good. I don't have the neutral switch wire hooked up but that never stopped me before. It originally started doing it with the silver ecu so I put the black one back in yesterday. I'll go swap them again to make sure.

 

Like I said its been running like a top before the Tranny swap. And for all testing I disconnected the turbo from the intake. Ran fine with it before.

 

Thanks for any help.

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Recheck your grounds on the manifold, and ohm out your cts 1st.

Ide think youd get some life with a wet throttle bore but you might consider checking the fuel pressure (wish these things had a test port!) plugging in the test connectors so the pump runs. Where is the pump grounded?

You have checked the ign system but have you verified spark and the quality of spark?

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I actually went out and checked spark after I posted this. Spark is getting to plugs, nice bright spark too. I know it's not that. Checked iac was opening by turning ignition off, couldn't blow through it, turned ignition on, could blow through it and here air in tb. Grounds are the factory ground on the intake. I'll check the cts. I'll look around for the resistance unless you know it and could tell me so I know what to look for. I have an electronic fuel pressure gauge hooked up to my old resing rate regulator but the regulator is backed out and on the return side because my return wasnt long enough to get to the tb. I just haven't gotten my other roll of fuel line out of storage to make a longer one. It does spike when the connectors are connected to about 10psI but it's not very accurate since it's on the return side. I spliced the spfi pump connector with the one off the carb pump when I went turbo with the carb. So it uses the original fuel pump ground.

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"I spliced the spfi pump connector with the one off the carb pump when I went turbo with the carb. So it uses the original fuel pump ground."

I dont dig that, but in all honesty its likely fine. 

 

 

Another quick check for you since im fuzzy on your intake setup. Make sure that the intake boot is tight at both ends and hose for the IACV is leak free and downstream of the MAF. While your there do a quick vacuum leak scan.

Edited by ihscout54
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I know it has good vacuum I have a vac/ boost gauge. It pulls 20in/hg at idle. BoBoth boots are tight. Iac hose is tight. I checked the cts, came out to 36,100 ohms.

 

That will be your problem.

Should be a max. of 12,000 at 14 F,

Less at higher temps

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The cts will cause it to not start?

 

Yes.the ECU thinks the engine is very cold and overfuels.

First clue was only starting w/the start signal ecu wire depowered.This leans the mixture.

 

Sounds like you have another CTS handy,but,if not,you could subsitute a resistor in the 5000-8000 ohm  range(simulating a semi cold engine) for testing.

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It works and it also roasts the hell out of the tires in 1st and 2nd gear. I have found the tbi system to be very forgiving in the air/fuel part of it. Although it goes stoic (14.7) in 3rd and 4th after it realizes exactly how much air it's sucking in but it riches into the 12's and 11's in 1st and second gear. I will be installing a cold start injector from a 91 camry in the boost pipe right before the tb unit for extra fuel under boost. Off boost it drives like a normal car, under boost it drives like a bat out of hell. Look up project Scubaroo in the members rides section. I updated it I think yesterday with a video from the rear seat facing forward of a 10mph rolling start and roasted the tires.

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can anyone yell out how many Ohms the CTS is capable of spitting out.

If one of us could measure a perfect operating engine to see how many Ohms at what temps, you may be able to bypass the CTS installed, feed the ECU the values say from a resistor wheel, give the ECU what it wants, rather than what the CTS can give it ?????

 

thanks for the pics too !! nearly forgot my manners :(

Edited by jono
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can anyone yell out how many Ohms the CTS is capable of spitting out.

If one of us could measure a perfect operating engine to see how many Ohms at what temps, you may be able to bypass the CTS installed, feed the ECU the values say from a resistor wheel, give the ECU what it wants, rather than what the CTS can give it ?????

 

Straight from the FSM,

 

-10*c (14f) = 7-11.5 Ohm

20*c (68f) = 2-3 Ohm

50*c (122*f) = 700-1,000 Ohm

 

Just don't get why the really cold reading is higher Ohm than the middle reading. But that's what is printed in the FSM.

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Already checked grounds again. Cts I had gotten was at 9000 ohms. But I went ahead and got the other cts that Tom had mentioned to me in another thread. Except instead of an import ignition brand cts I used a master pro to save a few bucks. I used master pro #2-9305 and connector bwd #28419A. I cut the pigtail off of the factory cts and soldered the wires to the new pigtail and the new cts goes right in place but uses a 19mm wrench. Went to start the car and it fired right up and it took less time for the idle to come down when warming up. I'll get some ohm readings from it when it cools down and fire it up and see where it's at as it warms up. Thanks again Tom for the part numbers and everyone else for the help! Luckily this is my project/toy and not my dd.

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