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Old 11-15-2009, 08:07 PM   #1
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Default Help with my ishty tune/starving student set up

So, took an engine machining class, had the ability to build a "project". Couple weeks earlier my 1.6 had failed due to a loose pulley bolt. Previous owner fail, and 5/10s fail on my part for not checking. So I thought, hell, might as well build myself a 1.8. Bla bla bla, couple months ago, I dropped a 94 block/99 head into my 1.6 car...

On a 1.6 ECU (I know I'm going to get **** for that). I ran out of money for a MSPNP.

Anyway, I have a strange power loss issue which is intermittent. Its not a huge fall on face flat power issue. Its just not a push you into your seat feeling like it usually is. Seems to come and go whenever it pleases. Sometimes I'm at a light and I don't feel much power, then at the next light it pushes me into my seat like normal. I know part of my lack of power has to do with a shitty 1.6 tune on an engine meant to make more power.
Did a compression test and got 160 psi on all 4. Worried, I then tried a cylinder leakage test, and got less then 2% leakage. What?? That's about normal leakage right?

Then I finally got my VICS working with an RPM switch. Besides this worthless piece of **** losing its settings every time the wind blows the wrong way, it kind of helped the power issue. But now I'm back where I was before.

Plans ahead: Finally install my f'n wideband (Been way too lazy) and use this RX7 AFM I have laying around and get somewhat closer to a better tune, messing with the AFM and what not. Yea, its not ideal, but honestly its kinda fun to mess around with, and I'm broke, so why not?

Anyone have any ideas? I don't even know what to check anymore. Yes, I know I need this/that/the other thing but school and other things really raped me financially.
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Old 11-15-2009, 08:33 PM   #2
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Forget the RX-7 afm, it doesn't do anything noticeable, and certainly won't help you with your tune. Could be any number of things, sorry I can't help more, but the bit about the AFM is my
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Old 11-15-2009, 08:35 PM   #3
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Get the w/b on and report what are some readings the w/b are giving you. Try and remember as many other parameters such as throttle % and rpm with the afr readings to help judge if the afr's are way off or if your problem is more along the lines of timing, ect.
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Old 11-15-2009, 08:37 PM   #4
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Forget the RX-7 afm, it doesn't do anything noticeable, and certainly won't help you with your tune. Could be any number of things, sorry I can't help more, but the bit about the AFM is my
Thats what I had heard but for a 1.6 engine. Since a 1.8 with a 99 head flows more air anyway wouldn't the AFM help even more then it would on a 1.6? I could be wrong but it makes sense to me. Unless the 1.6 throttle body restricts airflow anyway...
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Old 11-15-2009, 08:39 PM   #5
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Get the w/b on and report what are some readings the w/b are giving you. Try and remember as many other parameters such as throttle % and rpm with the afr readings to help judge if the afr's are way off or if your problem is more along the lines of timing, ect.
Just to confirm, as RPM goes higher, regardless of WOT or cruising, AFR should go richer right?
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Old 11-15-2009, 08:47 PM   #6
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No it should not. You have a ground issue plenty of people are up and running on 1.8 swaps everyday. I would check the FI grounds over by the injectors etc. This is a pretty common issue.

Good god people stop telling everyone to put a god damn wideband on essentialy stock cars. Dont you people remember what tuning is and was about before we all got widebands. He doesnt have a radical setup the stock ecu can hold him just fine.
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Old 11-15-2009, 08:49 PM   #7
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Negative, if you drive it nicely, it would stay between 14.5-15 a/f.

When you step on it more than i believe 60-70% it starts getting lower.. 13-14.. you wot it, it starts pulling at 12-12.5

This is for my 99 so perhaps a 1.6 tune will be very different.
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Old 11-15-2009, 08:56 PM   #8
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No it should not. You have a ground issue plenty of people are up and running on 1.8 swaps everyday. I would check the FI grounds over by the injectors etc. This is a pretty common issue.

Good god people stop telling everyone to put a god damn wideband on essentialy stock cars. Dont you people remember what tuning is and was about before we all got widebands. He doesnt have a radical setup the stock ecu can hold him just fine.
He said he has one just has not hooked it up yet, what harm could possibly come from simply hooking it up? w/b's are a great tool and just because people got by without them back in the day does not mean they should be shunned from using them today.
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Old 11-15-2009, 08:57 PM   #9
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Wait, I wasn't saying it actually was going either way, I was asking if it should. I have no idea what AFRs are at the moment.
Yea, 1.8 swaps run fine all the time, but do 99 1.8 swaps run fine in 1.6 cars all the time with 1.6 ECUs?
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Old 11-16-2009, 01:46 PM   #10
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Yea, 1.8 swaps run fine all the time, but do 99 1.8 swaps run fine in 1.6 cars all the time with 1.6 ECUs?
I don't see why not, i am doing it. My mspnp is a 1.6, however it tune-able. The fact that it comes and goes leads me to believe its something ground related as well. Triple check those two grounds at the back of the head and possibly clean them and/or change their locations and report back.
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Old 11-16-2009, 02:06 PM   #11
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Originally Posted by thesnowboarder View Post
I don't see why not, i am doing it. My mspnp is a 1.6, however it tune-able. The fact that it comes and goes leads me to believe its something ground related as well. Triple check those two grounds at the back of the head and possibly clean them and/or change their locations and report back.
Ding ding we have a winner.

As for the OP AFR's or air fuel ratios are a measure of the fuel being injested in your motor. Stoichimetric is 14.7 and most NA motors make the most power around 13-1 whereas turbo etc motors do to higher heat lvls and brake specific fuel consumptions like to run anywhere from the mid 12's to the mid 10's.
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Old 11-16-2009, 04:57 PM   #12
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I know WHAT AFR's are, I just don't know what MINE are. As for the grounds, I'll give them all a check tomorrow. The power loss happened on the way home right now, pretty irritating.

So is the overall opinion that I should ditch this RX7 AFM?
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Old 11-17-2009, 12:48 AM   #13
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I've been observing that this problem seems to get worse the longer I drive. From school to home, by the time I'm around my house the car feels weak.

Wtf?
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Old 11-17-2009, 01:34 AM   #14
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Yep braineack had the same problem check and make sure your grounds are good and report back. Also the car getting weaker the longer you drive it points to a dieing fuelpump maybe throw a pressure gauge, on there and let us know your results.
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Old 11-17-2009, 03:03 AM   #15
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Checking grounds tomorrow probably. Going to check fuel pressure eventually, gotta get a pressure gauge.

Any other ideas are welcome.
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Old 11-21-2009, 03:12 AM   #16
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I vote for a dying fuel pump. Had a similar problem in my 1990 about 4 years ago. The pump is certainly old enough to need replacing in a "maintenance" mindset.
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Old 12-16-2009, 01:56 PM   #17
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Didn't want to start a new thread for this. Copy pasta from power mods section of m.net

Ever since I put it in [my 99 engine], it has trouble idling on a cold start. During the summer months the idle would fluctuate from almost dead to 1000 and after backing out of my driveway(which is about 100 ft long), it would idle fine. Now that it has been cold, I have to keep on the gas to keep it from completely dying, and it starts misfiring if its REALLY cold. Idle rpm kind of fluctuates but not as much since my foot is on the gas trying to keep the damn thing running. Once I back out of my driveway and get to the stop sign at the end of my street (A total of 250 feet maybe), it idles fine.

I'm guessing it has to do with me trying to run this engine on a 1.6 ECU, and maybe something with the AFM and having to mess with it.
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Old 12-16-2009, 02:18 PM   #18
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Didn't get any reports back on the grounds.

Did you end up swapping a stock AFM back in? What have you changed since the problem has started?
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Old 12-16-2009, 02:22 PM   #19
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I've been ******* packed with finals and work and I am finally checking the grounds today. Havn't even had a chance to open my hood in like 3 weeks. Didn't check fuel pressure either. Which is why I asked this question, I didn't really want to **** around with 50 things to find my solution 3 hours later when I can get some guidance.
I've been on the stock AFM, havn't touched anything. I've been living with a **** cold idle since I got it running. Lazyass
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Old 12-16-2009, 05:56 PM   #20
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Checked the grounds right now. I've got 3 ground terminals on an intake manifold stud that isn't being used. Engine block to chassis ground is going from that stud to some bracket that holds the clutch line, but in between the bracket and the chassis. Ripped off the rubber which was hardened and wrapped it with electrical tape. Is it bad to have 3 grounds on one stud or something?

I've noticed my tachometer bounces around sometimes, and I've heard thats a ground problem but sometimes I'll hit it with my finger when I'm driving and it'll bounce back to where it was.
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