I don't know how to check for stuck injectors.

In additon to stuck injectors the o-rings around the injectors might be leaking. Therefore the car could be flooding itself when there is any pressure in the fuel system.

After we got the car going, we later removed the injectors and took them to a turbo specialist for testing.

They were running at 60% efficiency.

Including new o-rings (C$150) the cost to refurbish the rail and injectors was C$550. *

Once put back in the car ran rich, I suppose because the Power Fc was tuned to the ineffecisnt injectors.

New Fuel pulsation damper and Fuel pressure regulator cost C$350.

(Good to replace the FPD because the little rubber plug can rot out and gas will drip/squirt out.)

 

Oh one extra question I'll pop in here, what's the easiest way to get the splined steering shaft out? I've undone the upper and lower pinch bolts but it doesn't want to budge. Should I be able to just collapse it up into the steering column or will I have to remove the column (or rack) in order to get it out?

 

I believe you have to drop the steering wheel down. I thiink there is two bolts holding it to the dash bar. There may be several more at the firewall. Then you can pull the column out of the way into the cockpit.

 

Undo the two bolts at position 6. I don't think you need to remove the steering wheel. And likely the two nuts at the low end.

 

OK so more questions than answers here but just an update

I drained about a litre of oil out of the sump which got it down into the hashed region on the dipstick, and reinstalled the downpipe and the turbo oil feeds, and left the inlets off. Ran the car and it was pretty much the same. It fires after about three seconds of cranking, then the smoke and pulsing starts. it's enough to shake the whole car. it smoothens off immediately if i open the throttle slightly. in fact some times it sounds almost normal. except the smoke is there. and then when the idle drops down again, brap brap brap. after about thirty seconds of playing with the throttle the car just died and this time wouldn't start again. I pulled the leading plugs and they were completely clean and dry!

surely the big shake and pulse is the effect of running on one rotor? or would no firing on the leading plugs cause that too?

so I don't think it's the turbos, as leaving the inlets off isolated the oil seals into the compressors, and if it were the seals to the turbine the thing would run fine, just be smokey
the oil level is now correct, I suppose I should check that the filler neck is actually vented correctly, maybe I've cocked up and plumbed it somewhere silly

hoping I've just got a big inlet leak somewhere and am burning off ATF from the deflooding at the same time! I'll need to have a rethink and look over the whole thing again I think

 

should add that when I had the downpipe out I added a wideband sensor, so might be able to get some A/F values shortly. does oil fouling show up as rich or lean?

 

Oil should not be higher than half way up the hash marks.

 

So the rough running is happening when you are not touching the throttle and goes away when you touch the throttle.

When you are not touching the throttle the ecu is running things based on the inputs from the various sensors.

When you touch the throttle the ecu starts to react to the position of the throttle position sensor plus the inputs from the other sensors.

When the ecu is running things it may be getting bad info, or the things it is telling to operate are not operating properly.

I suggest you do the following:

1. Run codes to find out what sensors, solenoids, devices are not working
2. Do the compression test again
3. Get a smoke test done for any system leaks

 

If a lot of oil pooled in the turbos, it may take some time to burn off.

As your O2 sensor has likely taken a beating, you may want to put in a new one.

 

Sorry about the small pic. The diagram shows all the devices sending inputs to the ecu, and, in the lower section all the things the ecu causes to act.

You can try to guess which things are not working, or you can run codes and have the ecu tell you.




https://cimg2.ibsrv.net/gimg/www.rx7...0585d2f7e0.jpg

 

I have a power FC and hand controller so should be able to see if anything is giving weird inputs. I read there's an option to switch between open and closed loop, will see if that makes a difference. Will have to wait for the smoke to clear in the garage first!

In the back of my mind I am worried it's the oil seals, but can they fail suddenly like this? Or do they tend to go slowly over time

 

Info from the power fc is much more limited than the codes from the stock ecu.

You may have to go and check by hand devices like the ISC, TPS, MAP, coils, CPS, etc. with a multimetre to see if they are performing in the ranges set out in the FSM.

I have assembled a kit with spares of all those items (and more). and when we get stuck, we begin to sub in the actual devices to try and find a solution.

 

OK well I did a compression test and got 92 - 0 - 0 on the rear rotor

interestingly the first test I did was 0 - 0 - 0, so I'm holding out hope that it's stuck apex seals as one obviously came right after the first test. oddly enough the cranking pulses sound nice and even. But the numbers don't lie, I guess I'll pull the turbos off after all and give the seals a poke

 

I believe if any face is below 33, it will be read as "0". Your 92 might be a cumulation of 3x 32

I have seen 200-0-0. Go figure.

 

Compression readings aren't additive.

Two no Compression faces will allow the engine to spin faster and have less leak down on the face with Compression however.

 

If two face have zero reading, how do we get a reading on the third face?

Could it be the loss of compression is because of the side seals giving out on the other faces?

I.E., would you not need two working apex seals, to get one good compression reading?

Would damaged side seals be one of the causes of the OP having black smoke in his exhaust?

 

If apex seals are stuck flat, or otherwise compromised, could partial compression be squeezed backwards into oncoming faces. Thus accummulating until the good apex seals come around?

 

In general:
One bad apex seal will cause low compression in both adjacent chambers. The opposite face will have good compression (2 good seals on that chamber).
The one low number on the other rotor could be a bad side seal. Apex seals are good.

 

His original reading was 0-0-0. So did one apex seal loosen up? Maybe only one more has to?

 

I'm waiting for a really windy crappy day so I can back it out and rev the absolute crap out of it lol. going to be smoke everywhere! I think I might put some ATF in there and turn the engine over a few times first, give it a chance to work on all the seals

I wonder what percentage of "blown" engines turn out to be stuck seals once the shop tears them down

in saying that I am still preparing for the worst

 

Revving the crap out of it may send broken bits into your turbo impellers, taking out your turbo.

Further, if the damage is only moderate, like a damaged side seal, you want to save the condition of the inside of the motor as much as possible, so a shop can possibly reuse parts in a rebuild.

(Look up the individual cost of housings, plates, eshafts and stationary gears.)

 

Here is a thread just started by a local guy to here. Interesting to compare his internal engine damage to the compression readings he got shortly after a "detonation" event.

https://www.rx7club.com/3rd-generati...steps-1171325/

 

I've decided to pull the engine out. it won't cost anything to pull it out and pull it to bits. even if it turns out to be something benign like a stuck seal, pulling it out and replacing everything at 88k km should mean trouble free motoring for the rest of my ownership at least. plus there's so much else that I can do while I'm in there to future-proof it. Just a real shame as I have so much else going on and didn't really want to take on any more workload. but, I'll just go slowly and methodically, I thought about buying another engine but really there's no point until I know exactly what I need. exhaust and inlet is half out already so really it's just coolant, loom and gearbox to disconnect

 

Many get frustrated and cut the oil cooler feed line(s) as they sometime get corroded at the keg connection. Likewise people cut the part of the emissions harness that runs back to the sensors on the transmission, because they don't want to go under the car to disconnect them properly.

Try to avoid those traps.

 

ok so I pulled the engine out and pulled it to bits. Found two stuck side seals on the rear rotor, so that explains that
now trying to put a plan together for the rebuild. couldn't really find anything wrong with any of the major components, but just wondering if this discoloration around the exhaust port is normal, will it clean off?