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Discussion Starter · #1 ·
if you just swaped the spi for the 1.9 and your having trouble getting it to work, heres your answeres. most spi's have trouble idling after being swaped. the pcm takes a while to figure out that its a slightly diff motor. just give it a week or so and itll figure it out.


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:?: SPI cranks, no start
:arrow: bad splices on wiring harness.
:arrow: PCM power relay not functioning.
:arrow: Fuel cut out inertia switch
:arrow: CKP out of range from trigger wheel.
:arrow: MAF not functioning
:arrow: :!: If you cut or spliced your crank position sensor wire or plug, your going to need to get a new harness and start over. when you cut the wire it adds resistance. since the signal is such a low voltage, any resistance will throw off the pip/saw. :!: :!:
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:?: SPI starts, but wont idle
:arrow: MAF not functioning/bad maf
:arrow: USE SPI MAF WIT SPI(1.9=15#/2.0=19#)
:arrow: reset PCM
:arrow: hold key in start until it idles corectly.(spi might start-run-die a few times. after the pcm figures it out, it shouldnt do it anymore)
:arrow: Clean IAC
:arrow: Check fuel pressure.
:!: You can also help the PCM to learn how to idle the car by adding in a manual IAC valve.
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:?: running Rich after swaps or frequent CEL lights
:arrow: May be caused by too much turbulance in the intake tract. Have only seen it on 91-93's with the smaller MAF and a 3" intake but could also happen on 91-93s with stock intake as well. Solution is to use a 94 or later MAF.
:arrow: the 1.9 Maf/injectors are for 15#-- the SPI MAF/injectors are for 19#. if you use 1.9 MAF with SPI injectors, you ll run rich.
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:?: just turbo'd the SPI, wont run/idle
:arrow: if using "draw-thru" switch to blow thru.
:arrow: make sure BOV is closed at idle.
:arrow: fuel pressure
:arrow: too much/too little fuel(too big injectors)
:arrow: PCM being stupid. reset pcm.

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:!: other things to try

-check the crank sensor
-do a compression check
-get a tire guage and put it on the fuel rail bleed vlave to check pressure. it should be arround 32 psi at cranking.
-take a small light bulb and stick it in the injector conectors, if it lights up the injector is firing.
 

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:!: You can also help the PCM to learn how to idle the car by adding in a manual IAC valve like I did.

:?: Rich running swaps or frequent CEL lights
:!: May be caused by too much turbulance in the intake tract. Have only seen it on 91-93's with the smaller MAF and a 3" intake but could also happen on 91-93s with stock intake as well. Solution is to use a 94 or later MAF.
 

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Good post and all..But When I swapped mine it started and ran perfect for me except I ahd the IAC on backwards so it wouldn't idle. As for the SPI Maf..Not sure if its needed or not..Mine was a direcxt swap and runs fine.

John
 

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Discussion Starter · #5 ·
JohnScort said:
As for the SPI Maf..Not sure if its needed or not..Mine was a direcxt swap and runs fine.

John
well im telling you from experience with 3diff motors/maf combos that you do need to use the spi maf with the spi. the 1.9 maf will work but youll run rich. your choice
 

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i have a 93 with the real small maf and the spi motor... it ran and idled fine, but being so small i decided to put on a 95 maf. it has much better acceleration but my idle is WAY too low... it wants to idle at 500 rpm and sometimes stalls. what should i do?

with the maf, i just took the housing and sensor as a whole and plugged it right into my system... should i try putting the OLD sensor on the NEW housing? or is it something else totally?

i havent drivin it around much at all yet, just a few short trips... i just put it on yesterday.
 

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You'll need to reset the ECU. Unplug the battery for 60seconds and it will make the ECU relearn the new sensor.
 

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marclar said:
well im telling you from experience with 3diff motors/maf combos that you do need to use the spi maf with the spi. the 1.9 maf will work but youll run rich. your choice
Could it be that the people that have OBDII dont need the spi maf since the engine is already OBDII.Just wondering.
 

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Discussion Starter · #9 ·
it will figure it out as best as it can but it still comes down to:

spi:19# injectors
1.9: 15/16# injectors


the pcm has no way to know which is which. it just uses the signal and makes the pulse width.


say for example:

3000rpm at 100kpa, the maf would read a theoretical 2.5v signal.... with the 16# it would have about a 8ms pulse. with 19# injectors that same 8ms pulse will allow that extra 3-4# of injector flow to rich-out the mix... does that make since.?
 

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Well gas milage goes to the crapper, you foul the plugs and the cat, and it will stumble off the line.
 

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1Sleepy93 said:
Well gas milage goes to the crapper, you foul the plugs and the cat, and it will stumble off the line.
1996 lx, Having these problems with stock 1.9. Would swapping the maf to a 2.0 help this problem? I have a high hlow filter adapter, and so far no other mods. Not a newbee, just a learn as I go kind of guy, and before my scort, 90 percent of my 10 years of experience comes from carberated engines. Stil new to the maf/ injector deal. Thanks for any help. (plugs are fine)
 

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It will help a good deal. I found that my FPR wasn't working because I had a clogged vac tree so that was my main problem.

The 1.9 MAF will run the SPI but not at it's full potential. The injector difference is enough to throw stuff off to the point things start to suffer 15# vs. 19#. With the SPI MAF you'll get better throttle response and milage.
 

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1Sleepy93 said:
It will help a good deal. I found that my FPR wasn't working because I had a clogged vac tree so that was my main problem.

The 1.9 MAF will run the SPI but not at it's full potential. The injector difference is enough to throw stuff off to the point things start to suffer 15# vs. 19#. With the SPI MAF you'll get better throttle response and milage.
So basically you are saying spi maf = better throttle response and milage for the stock 1.9? Do I have to change the fpr and the injectors to get this effect as well or would this just make for more effect. Appricate the input, I actually have been studying the use of fule injection since I posted this question, I'm getting there :roll: ! You guys are most helpful.
 

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You have to use the SPI FPR, injectors, and fuel rail with the SPI. But you need to make sure the rail is of the 97 vintage if you don't want to convert fuel systems and ECU's.
 

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1Sleepy93 said:
You have to use the SPI FPR, injectors, and fuel rail with the SPI. But you need to make sure the rail is of the 97 vintage if you don't want to convert fuel systems and ECU's.
Im sorry if I sound repetitive but you said they must be used with the spi. I wanted to clarify that I was wnting to know the bennies of 2.0 maf when used on my 1.9, I have yet to do the 2.0 swap, I love power, but my funds are currently diverted to a carbon fibre project.
 

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If you were to use a 2.0 MAF on the 1.9 it would cause some problems. Mainly it would starve the engine for fuel since the 2.0 MAF is setup for 19# injectors. This would result in loss of power and possibly damage to the engine if a lean condition caused pinging.
 

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1Sleepy93 said:
If you were to use a 2.0 MAF on the 1.9 it would cause some problems. Mainly it would starve the engine for fuel since the 2.0 MAF is setup for 19# injectors. This would result in loss of power and possibly damage to the engine if a lean condition caused pinging.
Thank you very much. I fully understand you now. (no go on maf) Sorry it took me so long to get that. I was actually thinking that would happen, that is why I asked so many times. Miscomunication is all, no problem. I'm really glad that I didnt just do it three questions ago. Thanx for your help any way. SPI swap it is, after carbon fibre.
 

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sl2 said:
i ran no MAF. ran run idle fine. can't put the 2.0 on because the plugs are differnt. the 1.9 makes it idle right. i don't get it. the f(uking fan won't kick on either.
Make sure the fan switch is grounded.

For the MAF you can run either one but the 2.0 will get better milage since it's matched to the injectors. To run the 2.0 MAF you just have to switch plugs on the wiring harness.
 
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