1adzam

I am condensing a previous thread I had going to try to make more sense of what is happening and what I've done in order to maybe get some more ideas....

- 87 GXL

-just rebuilt the engine. Most internal pieces replaced... apex seals/springs, oc rings and rubbers, etc. etc.

-injectors cleaned and tested by Cruisin Perfomance.. they came back A+

-new fuel filter and thermostat

-the car will start right up and idle beautifully at 800 rpm's. Fast idle works just fine. BAC tested ok.

-does seem to run rich as the plugs are black. But I've run the car at idle for about 10 hours now so I can see that happening. Just replaced plugs with new ones and didn't make a difference with my problem

-the problem:
if I go from idle to wot all at once the engine just bogs down and will not deliver power with lots of rpm bounce. I get a weird sound from the AFM almost like the flap can't make up its mind to open or close. It flutters in other words. But it is not stuck it moves freely and springs back to closed position, I checked. The other problem is I can build power gradually to about 2,700 rpm's with no problem then I get the same condition as I previously described. I drove the car up my street and it seems to have a huge lack of power. As I previously mentioned, I have good compression and great idle but seem to lack good combustion/power for some reason.

What I've done:
-rechecked timing about three time including pulling the CAS and realigning it

-rechecked all conections both electrical and vacuum. It's all there and plugged in.

-swapped the AFM and CPU with others. No change

-checked all throttle connections and also checked the plates. They are free and are opening as they should.

-ran engine diag with my homemade tester (I love that thing) and received only one code which was O2 sensor but even that is intermittent.

- tested ACV. got some weird stuff here. Air blew out the valve into the air silencer tube at idle which FSM indicates it should only do at 1500 rpm's plus. No air out the relief solenoid tube. So, this may be a problem ACV. Anyone think that would cause the symptoms I am getting?

-Can't remember specifically but if I put the exhaust gasket on wrong and covered the little hole from the engine would this cause AFM problems. I just don't want to tear off the exhaust if I don't have to. I don't think I did this but who know's???

My other thoughts are that maybe somehow I am getting negative pressure back through the throttle body and back to the AFM. Not sure if that is possible but it's the only thing I can think of to make the AFM react the way it does.

Any thoughts or idea are greatly appreciated... I'm at a loss. Thanks in advance for any posts!

Previous thread if you really want to know is... https://www.rx7club.com/forum/showth...hreadid=218638

1987RX7guy

iTrader: (3)

Have you checked your water thermo sensor?

2a+RoN

how many miles are on the rebuild???

1adzam

Havn't checked the water thermo sensor. There are no miles on it. About 10 hours of idle time though.

HAILERS

******- tested ACV. got some weird stuff here. Air blew out the valve into the air silencer tube at idle which FSM indicates it should only do at 1500 rpm's plus. No air out the relief solenoid tube******

Most likely the water temp switch, located at the bottom of the radiator.....is not connected up. Has two wires. Disconnect either wire and the Relief Solenoid will not energize and pass vacuum to the acv, which in turn would stop the air from being dumped into the silencer.

This has 100 percent nothing to do with your problem. It should be a something that needs fixing someday prior to emissions testing.

HAILERS

******Can't remember specifically but if I put the exhaust gasket on wrong and covered the little hole from the engine would this cause AFM problems. I just don't want to tear off the exhaust ******

The little hole (approx half inch dia) is for the EGR. It should not be causing any problem. 90 percent sure your problem is not related to this in any way.

HAILERS

The water thermo sensor is on the BACK of the water pump housing. It has nadda to do with the temp gauge. It lets the ECU know the water temp so it can adjust the duration of the fuel injectors. I'd say it's hooked up since you have no codes.

Are you using the stock fuel injectors? They should have a number on their sides ending with the number 1350. They should also have a locating tab on the injectors to mate with the electrical plug that goes on them. This tab should be in the center of the injector. The wrong injectors will have the tab offset from center. Not good if that's the case.

Try disconnecting the TPS plug and go for a drive. Any different???

Also try disconnecting the vacuum hose from the pressure sensor. Plug the vac hose with a screw. Drive the car. Any difference????

Pull the TRAIL coil plugs off and go for a drive. Any difference???? Trail coil assy located near the brake booster.

The fuel lines. The line from the fuel filter should go to the front delivery line on the engine.

The LEAD plug wires can go to either position on the lower plugs. The same cannot be said of the trail plug wires. They MUST go to where they should go.

Try installing the jumper in the fuel check connector near the right front strut tower. Go for drive. Any better???

HAILERS

The CPU has nothing at all to do with the engine running. It's located near the left foot of the driver. The ECU is located under a plate that in turn is located under the passengers feet. Under the carpet thank you. Make sure all three plugs are on secure.

Now. The FIX. You forgot to secure the grounds on the top of the *block*. These grounds are the ECU grounds. Must be secured. They are on a ring looking terminal. Located a touch to the left side of the engine and towards the rear of the block. I think a 12mm head size bolt secures them.

HAILERS

About the timing. Take the black cover off it. Put the mark on the front pulley opposite the pointer. Normally the pointer on the rotating shaft should be just about a eighth inch or less from the center of the fwd black reluctor.

HAILERS

Go to this site http://www.teamfc3s.org/forum/showth...&highlight=cas where I and R7ENVY posted jpgs of the cas when the timing is spot on and the pointer aligns with the LEAD mark on the front pulley. Is your cas close to the pictures?

1adzam

It is hooked up. BUT, I have not tested it. It's possible it's not working
Yes

If you are referring to the ground strap, I did secure it. I believe there was only one wire though but I may be wrong there. It was almost two weeks ago when I put the engine back together but I will check it none-the-less
My CAS was set like the one in the factory set timing.

1adzam

Oh when i spoke about changing out the CPU I was referring to the ECU. Sorry for the mis-quote.

HAILERS

****My CAS was set like the one in the factory set timing****

Then if you took the black cover off and the pulley is aligned with the pointer.....your cas should look like the one in the pictures.

****I did secure it. I believe there was only one wire though but I may be *** two wires, I think. Seems you did it though. I struck out on that then.

***The water thermo sensor***** if it's hooked up it's probably ok. Hard to see how one would go bad.

I'd still pull the tps plug off and go for a ride. Then disconnect the vac hose from the pressure sensor and plug the line and go for a drive.

1adzam

Hailers... pressure sensor... what are you referring to??

88IntegraLS

There is an atmospheric pressure sensor in the passenger side foot well just in front of the door hinge, behind some plastic trim.

HAILERS

I'm refering to the Pressure Sensor on the right front strut tower. Perhaps I should have said Boost Sensor? I'm not refering to the atmospheric sensor in the passengers side of the interior.

It's just that the 1987 factory manual decided to call the Boost Sensor a Pressure Sensor on the Turbo cars and in the non-turbo cars calls it a Boost Sensor. They did that in the 1987 FSM.

If the boost/pressure sensor has it's vacuum line disconnected, then the secondary fuel injectors will come online at approx 3500 rpm whether or not the ECU detects a LOAD condition or not.

Normally the secondary fuel injectors will not come on line unless a LOAD is detected AND the rpm is 3500 or greater. But if a LOAD is not detected they will not come online even if your over 3500rpm.

I was just fishing when asking you to take the vac line off the boost/pressure sensor. Just trying to find something that will make a difference. Same with removing the trail coil/plug wires. A normal car will run just fine without the trail coil/plugs. I was fishing to see it the trail plug wires were crossed or the trail coil was amiss.

1adzam

Thanks Hailers. I figured you were speaking of the pressure sensor on the right front strut tower. Tried that but no difference... other than I got an error flash on the ECU tester... woohoo. I also tried everything else you suggested. No difference. I keep gong back to the the problem and the different conditions in which it happens. Idle to WOT lack of power and noise happens immediately. Gradual build to 2700 rpm's then it occurs. I look at the different scenarios posing the same ultimate problem. I'm starting to believe it is a fuel delivery problem. If the throttle opens up right away (idle to WOT) it gets no power right away which brings me to fuel. If I gradually build power it ultimately does the same thing at 2700 which again could be fuel delivery but because I built the rpm's gradually the fuel pressure can adjust slowly but not rapidly. What ya think??? But, I guess the opposite could be true... plenty of fuel but not enough intake air at either condition.

1adzam

Any thoughts guys. Think I'm on the right track?????

Templeswain

I don't have an ACV on mine anymore....BUt

I wonder what would happen if I tool my block off plate
and ran her for like a minute, if I could mimick your condition. But then again I don't know if that's a good idea.

I think you're on the right track. For these reasons:

Stock injectors. Tested fine and plugged in.

ECU swap. No change.

AFM swap, No change..

Water thermo sensor, No change

Pressure sensor. No change

I'd say. can you Manually make the ports open?

Is it possible to reverse the valve sleaves so that they're actually closing when they're suppose to be opening?

I'd speculate that the ports don't just open at 3500.

In fact I don't think it would matter what the actual RPM is, so to speak. The port as a matter of physics can't just instantaneously be open. There's an agregate related to the time it takes for them to open.

So perhaps, speculating, the ports begin to open at around 2700 rpms and are completely open at 3500 and above. But between say 2700 and 3500 the ports are in the process of opening?

Could some one more knowledgeble verify this assumption?

Damn I wish I had a clear, see through engine block.

Oh well, that's my theory. It sounds like a Air-fuel mix problem in the secondary port system. I mean, it idles just fine. But when you hit the gas, to engage the ACV for the secondary ports to open, the AFM freaks out and gives that sucking whimppering sound.

1adzam

Hey Temple. It would be possible to reverse the secondary port sleeves... if you clocked them the wrong way. In other words put the large end of the pin at say 1:00 on the left one rather than at 7:00 where it belongs. I have a few other things to check before I start tearing anything off of it to check those type of (bonehead) problems. I'm sure I did that one right because I was thinking that if they were on wrong you may not get any air after 3500.

Going to check the grounds on the AFM plug. Then I'm chasing down any fuel delivery problems such as the fuel pump etc.

Templeswain

Wazup.

See, that's the weird thing. A clogged fuel filter I'd speculate would cause idleing problems. If you reversed the fuel hoses, it probably wouldn't start and if it did, would die quickly. The pulsation damper I don't think could cause this problem, but i donno.

The real crazy thing is that you did the rebuild, and I'd say a damn good job of it too cause more then half of those that do can't even get the engine to start up again let alone idle. Yours starts but has this crazy problem.

When I primed the fuel system in mine a couple of days back I could definately hear the pump running with Ingnition to the on position. Not a faint pumping sound. A high pitched WRRRRRRRRRR. I would also think that if the fuel pump is laboring that something is in the way.

Maybe a pinch or crimp in the line?

Well, at the very least when you figure this out, I gots to know all about it.

1adzam

I was reading some more on fuel problems. It could be a crimped line. BUT... one thing I probably forgot to mention. This car sat fo almost 9 months. I bought it with a bad engine last January.. Oil control rings gone and lots of smoke but I never saw it run. I wanted a rebuild project and hey for $500 seemed like a pretty ok deal. Anyway, the point is, the gas was probably pretty old and could have even varnished up. So this may be the culprit. I also know the car had over-heated at some point but not sure how badly. I do know the rotor housings were not warped as I measured them with a micrometer. I think I have more in tools for this than I do the car LOL. Maybe my sig shoud read: Engine hoist, engine stand, micrometers, vernier calipers, inside micrometers, dial indicator, parts washer etc, etc.

Not sure if I mentioned it but I did do a compression test. 101 on the rear and 95 on the front. Thought that was pretty good for a new rebuild. Guys... this look OK for a new rebuild with 0 miles????????

Templeswain

But you still got it to start on a rebuild.

Impressive. No pun intended.

I sent you back a PM. Only about a Million years late. But I suck at PM's.

car idles. Bad gas should equal bad idle

1adzam

I did put some new gas in her before fire-up. My point is that the old gas may have blocked the lines or the screen on the fuel pump... just a little as to allow idle but not a fuller throttle position.