(11-20-2019, 06:17 PM)TomPrestin Wrote: todays information- then questions. fyi I'm getting paranoid that I'm destroying an engine I spent the last 2 years hunting down parts for.
old header was cracked, thrown out. new thorley header does have EGR port. looked extensively tonight at all vac hoses/connections, and header, all are connected correctly and don't see any leak points.
Scanner does freeze-frame when coded- freeze frame from today says:
DTC Code: P0400
Fuel System1 status: CL
Fuel System2 status: ... (not sure if this is applicable or not, but its listed in the frame)
Calculated LOAD Value: 19.6%
Engine Coolant Temp: 177f
Short Term Fuel Trim - Bank1: -1.6%
Long Term Fuel Trim - Bank1: 1.6%
Intake Manifold Absolute Pressure: 8.7 inHg (this is the EGR BARO RELATIVE sensor, NOT A MAP and NOT ABSOLUTE BARO at all. ) same as hand tool gauge does!
throttle is open (too bad freeze frames do not show all sensors. sadly)
Test B needs at least 22"HG vacuum (rel) 0.75bar so the above is TEST A. the above is the cruise test. failing. (it commanded the VSV valve open and closed and the change on BAR failed (differential test it ) it tells us only 2 things EGR main is dead, or the Exh path is blocked. (we do more tests to learn which of the 2 it is.
the only clues as to TEST A or B are the vacuum readings, high vacuum is B , lower is A, cruise.
Engine RPM: 2547
Vehicle Speed: 49mph
Doesn't say anything about EGR A or B. seems like something is missing.. you and me both. (that is correct only the numbers give it away)
yes the factory dealer scan tool has button to press to get A or B cause we dont have that in OBD2 tool land, so vacuum it the KEY to what is UP.
I took multiple other snapshots tonight while driving and then arrived home basic info listed here. not sure if it will offer any insight but I'm at a loss on it. especially the low vac pressure:
DRIVING
SnapShot1:
Long Term Fuel Trim - Bank1: 0.8%
Intake Manifold Absolute Pressure: 15.6 inHg
(this is not normal MAP sensor it is EGR MDP sensor and uses relative reading) noW I Know you dont own a vacuum tool (first time)
Here is the true output MDP, https://fixkick.com/sensors/EGR/EGR-map-test.html
At WOT, (or just keyon) Absolute pressure is~ 29" HG or 1 BAR (sea level all) ( this is normal at sea level , air pressing down on you an car and MDP)
At idle , Absolute, is at 19" or 0.64bar
now we do , relative pressure, is against , actual atmospheric pressure. of 1bar. R = 1Bar Absolute(now) minus reading) this is what a hand tool does, this.Relative.
so WOT is 0BAR (1 minus 1 = 0) math. very different readings. for sure. than above.
idle is 1bar minus, .64bar and = .36 bar, and .36 is 10.6"HG, this IS HOW THE MDP works on this car, and is only and EGR sensor, just for it alone.
MDP does this, and your tool LIES (marked as Absolute is the lie only, not the data) and told you it was 8. if you had used hand vacuum gauge you see 19"HG. it idle.
the hand tool is 0bar disconnected, Relative. Just like the MDP. so is NOT a MAP sensors it is Relative BARO sensor. MAP means manifold absolute pressure, and MDP is NOT That.
the MDP uses these spec, rules. https://fixkick.com/sensors/EGR/EGR-map-test.html
Engine RPM: 3030
Vehicle Speed: 75mph
Ignition Timing Advance @Cylinder #1: 33.5degrees
Snapshot2:
Long Term Fuel Trim - Bank1: 1.6%
Intake Manifold Absolute Pressure: 12.9 inHg (relative MDP and is not a MAP)
Engine RPM: 2585
Vehicle Speed: 66mph
Ignition Timing Advance @Cylinder #1: 30.5degrees
Home, Idle hot1 (no accessories on):
Long Term Fuel Trim - Bank1: +2.3% (o2 reads -2% lean ECU goes +2% rich) all normal.
Intake Manifold Absolute Pressure: 8.1 inHg (not this is 8, MDP relative pressure not absolute, tool lies on name. a hand tool shows 1 (relative MDP and is not a MAP)
Engine RPM: 787 (idle)
Vehicle Speed: 0mph (parked)
Ignition Timing Advance @Cylinder #1: 10.0degrees
Home, Idle hot2 (no accessories on):
Long Term Fuel Trim - Bank1: 3.1%
Intake Manifold Absolute Pressure: 8.1 inHg
Engine RPM: 803
Vehicle Speed: 0mph
Ignition Timing Advance @Cylinder #1: 9.0degrees (all above is normal, only the word absolute is dead wrong "name". (relative MDP and is not a MAP)
To add to the confusion cold idle is now very high. (this is all very normal the IAC open more if the air temps are colder, all fully normal. (well depends on how high.)
when talking about cars and UEFI TELL THE Helper out door temps, and altitude, (for the latter, in feet or say near sea port or, some clue, ok>?
I guess not really cold and in florida? (where the grow oranges or KEY Limes (yum)
too high idle means vacuum leaks, (cold)the ISC and the IAC are the only normal leaks by design)
any leak from intake valves to MAF is a leak. (no that maf is not a leak) The TV is closed at idle.
There are some tests to do to find leaks, (air) unplugging the ISC connector, makes it close 100%. (if not stuck open)
The ISC has 3 hoses,(2 are water) 1 is air you can pinch the air hose and if idle drops to the good zone say 1500.. cold the ISC IS STUCK open.
testing the IAC is super hard. (the 8valve G16a is vastly more easy to test.) not to mention, pinching all air hoses. small.
The IAC is bolted below the TB, and the bolts love to seize making it damn hard to do that hot water pan on stove tests, I like to do.
On can starve it from all air inputted to see its CONTRIBUTION to air. (rpm drop actual) IAC is closed 100% at 150F temp, water, so its colder we want to test it at. The hole is in the TB front air horn bell. HERE. (have you found the TB air bleed screw yet and it not missing?)
that is just 2 sources for leaks there are vast more.
all vacuum lines
all diaphragms even that brake booster)
the injector cushions leak, if not new. sure they are I think. new.
cracked or bad VSV (all)
the main air pipe huge up top can crack, anywhere there cracks (even mounts broken off and leaks air) and the large rubber connector fittings to same bad.
That is about it, but sure gaskets too.
finding vacuum leaks is skill set,,, using propane gas trick, pinching lines, vacuum leak down testing hand tool, sonic leak detectors (a tool) and the SMOKE machine. One guy here (he was at wits end) 8v, we found after doing all tests, every single one to no avail the smoke machine nailed this.
the silly car at one time was parked in 0F degree weather with only water as coolant (in FLORIDA) the water now pure deep inside the TB IAC, forze
and ICE expands when frozen and this cracked deep inside the TB cause and air leak, in the IAC, and high IDLE. where no human can ever go, by the way.
yes vacuum leaks can be a HUGE HORROR. (some are easy some are a horror)
one guy even put his hand over the air horn (do not do that) and he found his engine runs with no air there, OOPS , deep deep damaged.
even intake manifold leaks in very hard to find places...
hope my vacuum stories help you.
Upon beginning of cold temps (how cold?) here it would run 1500(ish)rpm when cold, then settle right down when warm. common in temperate climates.
Now running 2500-3000 cold, settles down as normal when warm. 3000 is too high, for sure in Florida. (im in TX, was 78F yesterday see? )
( ok in maybe Alaska 3000? IDK, but never been there, , but for sure more RPM THERE, maybe 2000 max is my guess.)
The 16valve engine only races too fast or only 2 reasons. (throttle cable not set too tight, will do it, 10mm slack is FSM spec on TV cable and cruise cable)
1: the 2 air acutators
2: Vacuum leaks, other.
IAC messing up or ISC sticking. both add air (metered air ) the engine, and do stick when old. car is old,
IAC is cold engine fast idle device.
If engine is rich, as it sure is cold for fact, any #2 vacuum leaks of any kind will cause HUGE IDLE speeds cold. (fuel + Air = fast idle)
Simply a change I thought might add insight to this conundrum. (and is correct, all evidence good bad or ugly helps Diagnosis. for SURE.
Still doing newly revealed mild hiccup also, mostly at cold idle and also at barely open throttle- cruising. (if you have vacuum leaks, hiccups are common)
I'll send pictures of engine bay tomorrow when sun is up. (no hurry but I know what belongs there and not, so showing me can help)
First off my comments are for all G16b and all things that can cause problems, I can not discount things, I can't see or know or, any of that , so I show all things for cause. I did not see you set belt tensions all wrong, see? (the belt must never be set to 100lbs tension ever , it fits loose using tiny spring or it will fail)
but did not , as say car runs great, mostly. do you have the crank pulley 17mm head bolt set to 94ft/lbs as the FSM and TSB DEMAND, (this is a day 1 fix on all G16)(retroactive to 1989 up)
My paranoia and lack of experience leaves me with these questions (in response to your check list) tonight:
1. Is is even possible for the engine to run as well as mind is with incorrectly timed cam? (not it can't run right like that)
Been my daily driver since I got it all put back together in April.
My assumption (very possibly wrong) is incorrectly timed cam would result in pretty dramatic loss of power (so true) and awful gas mileage? (see green line above)
2. Upon more reading on the site today, says cam is timed at #4, but then in instructions for setting timing say to connect timing strobe to #1 SparkHV lead. Is that correct?
NO spark is set at #1 wireHV TDC firing, the CAM is timed at #4 firing, period. the 1996 FSM is free and linked in the sticky first post here on this BBS.
The cam cog on this car has 2 false marks, are you aware of that.?
The engine after full assembly and good shop does compression test, to see if all that hard work paid off. did you? this is first step, then top end oil checked , just cranking a cold new engine, with spark or better FI fuse pulled so fuel stops flowing, we check that the cam gets OIL, if not stop do not run any new engine every , skipping these first steps.
the make sure oil gallery pressure is good, on a cold engine it is near 50PSI, (cold cranked only , no fuel) then I attempt to start the engine)
I never just throw and engine together and start it up. not me, seem so my do that and wreck a good engine. sad to watch.
The next step is get the vacuum tool off the shelf or tool box, and check vacuum at idle 800rpm hot. see 19 or 20 " easy. HG inches, Relative vacuum is 0 HG key off.
Once you get this far, you know that Vacuum is AOK. and that he scan too lied to you (vast do this) at (relative MDP and is not a MAP)
You need to know that,for EGR , the EGR MDP sensor , work in RELATIVE mode not ABSOLUTE mode..
I followed those instructions at original reassembly, so not questioning, just confirming to eliminate variables for my own piece of mind. I'm sure you did but my posts are for
all things that can be wrong, seen Timing belts done wrong vast times or belt too tight and it shreds.... keep and open mind and win., things can fail even new things.
3. I'm just plain baffled. ( don't be we are collecting Evidence, and you did GREAT !!!!!
Trying to keep an eye on O2 graph readings while driving, both seem to be swinging as if working correctly, but I am sure no expert. (get a helper to drive and you look)
No need every to work alone if doing dangerous tests, use 2 persons, my Laptop has record mode, and can log live data (and filtered) all day long. no hands
how you log , can be easy or hard or dangerous. (see my photo above with tons of wiggly lines, that was recorded, all that was)scantool.net. _+Palmer scan software.
I own this software called Palmer. (nothing Ive seen is better or for sure more safe to use (hand free logging) (push record, drive, stop , push play back,.)
the O2 sensors, are not static, at all, they measure 02 and the ECU hunts the mixtures constantly never ending (hot engine) and those readings you see are like scope
each time the voltage crosses 0.45 (center) (called cross counts) that is the ECU doing that with fuel mix, trim, it is a dynamic ECU servo action, no different than idle speed ISC or cruise controls all are servos.... they hunt to attain perfect, all do. but the O2, hunts deeper on purpose to keep that CAT hot (by law, and by Physics of the cat)
So if it is cross counting like my photo clearly show, and the swing go near 0v and near .9v then all is well in trim land and 02 land. sees so to me.
The swings end at WOT< and if you move the throttle fast. the come back as you cruise steady or just idle (hot engine )
Only time no swing, is at closed throttle while moving (hard deceleration or WOT) all O2 values drop to bottom until throttle is reopened.
I download that info and post as soon as possible also.
4. Paranoia says I timed something wildly incorrectly, but its hard to believe that's the case as its capable of running stably, consistently, been my daily driver since the early spring, with no obvious signs of problems other than this CAT burnup or deal.
Thank you for all of your input, knowledge and suggestions.
The engine is running ok, I see that in the data so far.
the EGR is dead, but we can fix that,
(so far we have cat melts, cat breakup inside, and EGR dead, and bad cold idle and hiccups, any more?) evidence.?
Let me explain limphome and only for EGR.
some of these cars (and by law) if the EGR fails, that means the car is NOX polluter, for sure. (driven hard)
the ECU seeing EGR 400 fail, may in fact go rich NOW, and this can and will overheat some CATS. (depends on maker of cat and mode)
if you have NOX, the best solution of all to ending NOX is to go rich, Rich cools combustion and NOX ends NOW.
this is in fact mandated on some cars then and now. dealing with NOX is serious (acid rain and burned lungs ,etc)
so the car may run perfectly until 400 sets, and then goes rich, not saying yours does, but many cars do.
It may also flash the CEL lamp (missing on your car) and the flashing CEL means CAT burn up , is soon, the operators guide tells you to not pull a trailer and drive slow and fix car.
I'd say all is good, but EGR failing and CATs melting, only why remains.
The cat some sold new are what I call weak cats, unlike the 1996 robust cat, the new cats do not last long of fuel mix goes out of control and for long time (weeks)
By the way thanks for sharing your data. (data is king)
The EGR test #1 is first.
at the MAIN< and is behind the exhaust manifold #4 runner rear, and very hard to see much less touch. so we use hand vacuum tool like the video shows.
and see RPM fall from hot 800 to 400 or stalls, end test.
we do that first.
then check the bark tube for barking pulled, I call that the bark test, (putt putt putt) keyoff, tube pulled (below MOD) and start engine hear the tube port bark. loud.
if not there are 4 places this blocks, EGR main (bark port)packed in carbon, intake mAN- S bend packed, head tunnel packed and the Thorney tube packed in carbon.
if bark passes. last is the live test all this in covered on my EGR page, step by step
next is LIVE test but your car has no real speedo, VSS must work or the EGR will be dead,, on all these cars. (1993 and newer, approx but 1996 up for SURE)
the EGR will never open at 0MPH ever,by hard coded ECU internal firmware logic.
also clean the MDP, just get its port on the bottom clean, no gunk there, so it can work right, (note I assumed it is 1996 old , here)
the plenum on theses cars are a mess, (the EGR cloud hits the PCV valve, could and forms GUNK, this gun lands all to easy on the MDP port) making read wrong or go slow.
The ECU is lame, the OBD2 should check the MDP 3times, by it self but does not, keyon, idle and cruise test.
but no it does not it just does the 2 EGR tests. and one fails.
Im not sure (im not firmware genius) but if EGR test A fails, test B may be aborted, A = Cruise test, B= moving fast cut fuel tests.(throttle at 0)
test A proves EGR main opens,
test B proves EGR main closes.
it does differential MPD readings to do that, (it does test A valve closed then opens it and gets 2 readings from MPD, and the difference in MPD pressure, is checked, (pass/fail)
MDP page.
the GM EGR truth page, A and B. (hard to find but I have it) PAGE1 and PAGE2
cheers and good day.
http://www.fixkick.com