(11-11-2020, 04:14 PM)Clint09 Wrote: First ever post for me here. I’ve been struggling to get my USA 97 16v running properly. The most obvious symptoms are poor mileage (18-21), very rich exhaust at idle, a code for bad catalytic converter, and an occasional misfire. The previous owner told me the catalytic converter was al busted up inside so he hammered it all out and it is now gutted. I Have been testing different things and it seems that the EGR doesn’t work properly. The EGR passes the stall test but when I rev the engine (with rear wheels turning) doesn’t seem to move the EGR diaphragm at all. After more research I learned that the EGR needs the CAT in place to function properly. So I have plans to reinstall a CAT but I am wondering if this could also be the source of my rich exhaust issue or is that being caused by something else? According to a scan tool all other sensors are reading fine. Also what would be a good option for a replacement CAT?

(11-12-2020, 12:36 AM)fixkick Wrote:

(11-11-2020, 04:14 PM)Clint09 Wrote: First ever post for me here. I’ve been struggling to get my USA 97 16v running properly. The most obvious symptoms are poor mileage (18-21), very rich exhaust at idle, a code for bad catalytic converter, and an occasional misfire. The previous owner told me the catalytic converter was al busted up inside so he hammered it all out and it is now gutted. I Have been testing different things and it seems that the EGR doesn’t work properly. The EGR passes the stall test but when I rev the engine (with rear wheels turning) doesn’t seem to move the EGR diaphragm at all. After more research I learned that the EGR needs the CAT in place to function properly. So I have plans to reinstall a CAT but I am wondering if this could also be the source of my rich exhaust issue or is that being caused by something else? According to a scan tool all other sensors are reading fine. Also what would be a good option for a replacement CAT?

OBD2 USA rule #1 (mine) is dot not worry P0421 cat codes, until the engine is fixed (EFI and all)  CAT errors are normal if the engine is sick, and is.
18mpg is horrid.
ok gutted, and break ups are common and so is that act, if not in smog testing state no worries there.
The P0400 error (DTC) will be endless as will the cat error P0420 , P04xx errors endless all, no Cat,
the cat missing on these cars, kills dead EGR so EGR errors P04xx hit. all 100% normal for missing cat or rodded out.
EGR uses cat back pressure to measure engine loads,  to inject EGR Gasses at the correct rate
The Cat misssing means the EGR mode will be dead, how can it not be dead. in this case.
but lets forget all the above for now... focus on spark and fueling, if compression is 180psi all 4 cylinders, done WOT.


The scan tool is handy but you need to look more carefully.
Rich means, 2 things, (besides gross misfiring bad spark, parts, ever do full spark tune up?)
1: fuel pressure is too high. (FPR dead as most are this old) (need keyon pressure  and idle pressures to know) no fuel leaks out vacuum nipple FPR.?
2: 02 sensor fibbing, or just the #4 exhaust tube heater crack sucking in air making the o2 lie all the time.
QOD:
1: is the o2 in closed loop at HOT idle.
2: is the O2 sensor scanned, swinging at hot idle.
3: is coolant at 180F for sure in scans of ECT at 180f or above?
4: drive car lots with O2 unplugged, Ignore DTC, errors, and get better MPG and end black exhaust smoke and raw fuel stink?

lots more but this is a good start.

It has new plugs, wires, cap and rotor within the last year. fuel pressure is around 45psi, compression is mid 170s on all cylinders, Fuel pressure reg is new and tested working and not sucking fuel through the vacuum line into the intake, I did notice the #4 manifold pipe is cracked. I didn’t realize the cracked manifold would suck in air and mess up the o2 sensor. I’ve unplugged the o2 sensor and drive for a while but didn’t notice much difference. Maybe I’ll try that for a full tank of fuel and see if the mileage changes.

(11-12-2020, 05:10 AM)fixkick Wrote: keyon pressure is 36 and drops to 30psi on mine,

43 is max no matter what.
what matters most is the 6 PSI change from keyon to idle.
that matters big time if you go to full throttle the PSI will to down to near keyon pressure  as low as 30

why is your pressure so high?
is the return line partially blocked/ or pinched, but what matters first is the 6PSI above,

good report  so far, you have handle on what was done and what might be wrong still.

Not sure me if this year has limphome for P04xx codes, I do think not, but.... nobody knows all ECU that well.

(11-12-2020, 01:42 PM)Clint09 Wrote:

(11-12-2020, 05:10 AM)fixkick Wrote: keyon pressure is 36 and drops to 30psi on mine,

43 is max no matter what.
what matters most is the 6 PSI change from keyon to idle.
that matters big time if you go to full throttle the PSI will to down to near keyon pressure  as low as 30

why is your pressure so high?
is the return line partially blocked/ or pinched, but what matters first is the 6PSI above,

good report  so far, you have handle on what was done and what might be wrong still.

Not sure me if this year has limphome for P04xx codes, I do think not, but.... nobody knows all ECU that well.

I rechecked fuel pressure it’s at 42psi with key on and 35psi at idle. (good)
I took the entire return side of the fuel system apart and could blow air through it so that’s not restricted. 
I put about 40 miles on it with the o2 unplugged and it still runs super rich at idle possibly even worse than before. (ECU  sees that and punishes us)
Just got done running a NOID light test on the injector wiring connectors and they all blink and seem to be working normal.
Also I forgot to add that when I started trying to figure out this issue about 6 months ago the EGR passages were plugged and the intake manifold was caked with black sludge inside so I took it off and ran it through a parts washer until it was spotless inside.
I noticed today looking through the throttle body that it is starting to build up black grime inside it again. (all normal for EGR + PCV cloud of death)
EGR is dead now so is just rich fuel cloud and PCV cloud there making carbon.  The EGR main can be defeated with vacuum nipple to it unplugged and Golf tee the free hose end so it can not suck air.
I presume the injector leak down test passes?

ok FPR is ok, and no return line issues.
It is rich,
what is your OBD2 data look like, hot engine fully , a hot idle 800RPM , does 800 work and hold with head lamps on and heater blower turned on and off?
OBD2 scans.
1: closed loop. true not false.
2: LTFT?  (fuel trim)
3: ECT at 180f? or more? 300 ohms hot. (see my ect page)
4: MAF flow.    1.5–4.0 grams per second  idle hot, 800rpm,  and gunned to 2500 goes to 10-GPS. parked ,  driving looks like this (real and hills)
will your scan tool do at least this below?  (simple code readers are mostly useless) real scan tools are very useful.
5: O2 scans. below.

the engine is running rich,  I bet the scans show that too.. but I can not see them.
The fuel pressure is ok;. engine OK, exhaust man NOT OK.
O2 can fail at any time in road trip as that crack widens, then shrinks and very odd thermal dynamic actions of any crack here.

this is the super cheap scan tool (hand held) that can do even this.... act.

this is the O2 swinging, fast.  and not stuck high , not stuck low and the heater in the O2 is not dead. (sure plugged back in)
B1S1 is bank1 , s1 is front sensor, the rear is useless for fuel trim.  note the deep and full swings here and  not offset high or low. centered it is.
when the #4 exh crack widens it sucks are and this signal slams to 0v and ECU goes full on rich( LTFT way off the scale)


EGR flow, dead parked,  only moving and the large hump is the barkpressure from the cat , causing more flow via Modulator.

1. wrong 02 used? not the Bosch correct 4 wire? (ask)
   
2. bad wires to the 02, heater or the CELL (+-) inside. they love to burn as they hit
   
3. exhaust cracks. near front sensor 02 putt fail put fail. (luck)
   
4. the gasket at end of header, missing cracked or loose sucking in air at PUTT + B.
   
5. engine not at 180f but cold. (ECT 300 ohms hot or scan shows 180f+)
   
6. injectors leaking or   1 dead as it mindlessly pumps fresh are (engine is air pump) to 02. and it fail. (each misfire is wasted fuel)
   
7. Gross misfire, some cheap carbon spark wires even new are bad, use only MAG wires on this car and gain even better spark than stock. spark gap 0.028"
   
8. ECU stuck in limp-home mode and suspends closed loop. and runs rich; all do that. only scans find this.
   
9. MAF gone wild (rare, most go lean never seen one ever stick high) see live maf PLOTS on these post. from me. 2nd post same thread.
   

(11-12-2020, 11:35 PM)fixkick Wrote: as you can see driving and plotting any errant OBD2 car can be really revealing. above software is. Palmer scan software


https://www.palmerperformance.com/store/product_info.php?cPath=21_26&products_id=36


even log CVS files and import them into Exel. and graph anything you what, even hours of data.