89 vette FI issues...2nd engine.. same problem

N

NewGuy13

Member
Hello all,

First off...Ive been lurking on these pages for many months now. I bought my first Corvette about a year ago...i'm now up to 2 (a 93 problem child in itself.. more on that in another thread).

The history of ths 89 TPI is as follows: The person I got if from sold it to me with various issues, I knew this full well and felt confidant on fixing it...stil do the price was right. At that time, the engine and tranny (auto) had separated by a half inch, was only being held together by the torch converter bolts for the most part. The engine did run, but very poorly. Ive since replaced the engine with a 500 mile engine off CL (kept the original and will rebuilt at a later date). Got the original aluminum heads rebuilt and assembled everything. I also went thru the tranny while it was out, replaced seals, bearings, converter.

OK.. here is the meat of my issues. The new motor is having the same issues as the old motor...! Ive narrowed it down to some sort of fuel ignition issue. BTW, I have a new distributor yet using the old coil (this might be somthing to look into later on). In an effort to not just replace parts at a whim. I'm trying to sluth this out. So far Ive done the follwing:

1. verified with a NOID light that I have a signal ateach of the injector harness points (all 8) good light at each.
2. I can unplug the following injector wires and the engine continues to run(poorly) without change: 1,3 and 6. If I unplug any of the others the engine idle obviously changes
3. new injectors from Standard (AutoZone)...it was a value build...

The one thing I have NOT done is check the fuel pressure, however I have replaced the fuel filter when I got the car.

In retrospect, the original engine was a mess (few and far oil changes, oil leaks.. etc etc...), however it did have decent compression roughtly 150-157 each cyl. With the exact same issuese with this motor as the last (yes I know.. I should have done the sluting sooner), it seems to be something common with between before and after. I would think the ECM, however witht he NOID lights showing a pulse... i cant think the ECM is the issue


SO....I ask for help thoughts? Fuel pressure.. fuel pump... ECM....injectors or... what am i missing... someone give me hints.. :)


Thanks to ALL!
 
logic says if you have a potential injector issue , you should test too prove it, you said

" 2. I can unplug the following injector wires and the engine continues to run(poorly) without change: 1,3 and 6. If I unplug any of the others the engine idle obviously changes"

[color=#008000Assuming youve checked that you have ignition spark at all the spark plugs , and theres no mechanical issues like worn cam lobes or busted valve springs the obvious test would be, to first do a vacuum leak test to verify thats not the problem,pull the spark plugs and label them as to the cylinder they came from and post clear detailed pictures as a great deal can be indicated by the condition of the spark plugs and because the cylinders mentioned are not all near each other or following each other in the firing order, you need to do a few tests, an IR temp gun and a multi meter would be useful, then if you don,t find a vacuum leak, to move those 3 suspected defective injectors one at a time to a different cylinder location and see if the problem, or issue follows the injector as its moved or stays at the current location,, obviously if it moves with the injector the injectors defective and if it stays at the current location with the currently working injector you swapped from one of the other 5 working cylinders its not the injector but an issue like a worn cam lobe, ID also strongly suggest measuring the ohms resistance on all injectors and posting the results you should get nearly identical readings on all injectors in the 12-16 ohms range[/color]
Id certainly throw two cans of injector cleaner and 4-6 oz of MARVEL MYSTERY OIL in a tank of fresh high test fuel, as that could help clear up the problem, but ID also test to see if you have a CONSISTENT 37psi-42 psi of fuel pressure at the fuel rail and verify the pressure stays in the fuel rail after the engines shut off for at least 5-6 minutes before it slowly drops, if it starts to drop off rapidly the fuel pressure regulator, fuel pump or one or more injectors is obviously leaking fuel.

yes it will take a bit of testing and reading but this is certainly something you can isolate and correct

viewtopic.php?f=62&t=882&p=1390&hilit=+propane+leaks#p1390

viewtopic.php?f=70&t=7309&p=24862&hilit=+won%2Ct+idle+injector#p24862

viewtopic.php?f=32&t=1401

viewtopic.php?f=32&t=6011&p=18597&hilit=+won%2Ct+idle+injector#p18597

viewtopic.php?f=32&t=596&p=14674&hilit=+won%2Ct+idle+injector#p14674

viewtopic.php?f=80&t=728&p=9217&hilit=+won%2Ct+idle+injector#p9217

viewtopic.php?f=32&t=3406&p=9014&hilit=+won%2Ct+idle+injector#p9014
 
I'll follow your thoughts, Ive been reading about them for a few weeks now, thanks for the the reply.

I roughly remember the exact same cyls having the similar issues with the original motor. Subsequently, it sounds like the bottom of the engine is rattling around (same as the last engine), I even went as far as to remove the valve train spider and related valve guiders (they link the intake and exhaust lifters then the spider holds them down) and baffels in the oil pan. At this point, my theory is that since 3 of the 8 cyls are not firing (oh.. and I checked the spark at each plug.. bright blue and hot at each plug and wire).

I'll check the Ohms at each injector, these are different than the original injectors in the last motor...oddly the last motor...if you unpluged certain injectors the motor would run better.. im thinking it was a ground issue of some sort. The wiring was not all complete when I bought it, it was clear someone with far less knowledge than I tried to working on the car. I did hook up other grounds as I found them, however perhaps I didnt find all of them.

I should add, I've even tried to use an automotive stepescope as well, when I unplug one of the suspected injectors the click click click goes away.. with i plug it back in.. it comes back...a basic indicator that the injector is working. They make the same sounds as one of the injectors thats known to be working well.
 
don,t over think it,
just try careful testing and take notes on what you find, don,t trust to memory, perform the tests like those listed above and post your results and we will go from that point
 
Ok, all the injectors were showing 16.4 with a -+ of .1

As an alternate test, I found the old injectors, a few of those were in the 14's howver a few were in the 2 and 3 area.

Fuel system next?
 
Update: as hard as this is to admit...I did make a mistake with the firing order. That did solve one of my issues. Now only 2 injectors are problematic. A refresher on my issues, originally I could disconnect the injector wire and the spark plug without the engine changing idle. All this after an engine switch out. The engine does idle better, and rev up faster, however I still have a nasty knock, I'm starting to think that's related to the hydraulic valves being out of adjustment. I did acquire a fuel pressure tester, at idle the engine has a constant 38 at the scheder valve. When the engine is shut down, the pressure slowly drops to 20ish over the course of 2-4 mins. Is that normal?

I'm still going down your list of tests. Any thoughts on my current progress would be appreciated.
 
it should take longer than 2 minutes to drop off that far (38psi-20psi) Id suspect the regulator diaphragm or an injector leaks,
but ID also adjust the valves at idle to only 1/4 turn past the point they click at idle speed, before worrying about tracking down that issue

viewtopic.php?f=52&t=196
 
Actually... before I read your response... I adjusted the valves while running this morning. I did back off the valves just to the point of clicking.. then did a 1/4 turn to quiet them down, to each cyl, each valve. I HATE doing that.. usually makes a little oil mess.. and its always hard to get the passenger side valve cover off. The idle slightly improved, however still is poor. I was still able to pull 2 of the injector (and distributor) cables without the engine changing idle. It still sounds like the idle is not what it should be. The car stumbles and idles poorly if driven...in fact I finally was able to drive it a couple miles (first time since the engine install)...seems like at a higher throttle the engine responds well... not sure if that's because the RPM increase hence the fuel pressure increases.. compensating for a flaw in the fuel regulator diaphragm. I did tape the fuel pressure tester to the front windshield and watched it increase as the throttle was pressed down (to a point). Unfortunately as I increase the power and speed of the car.. oil began to spurt out of the dipstick of the engine..the way I saw that was the smoke and smell coming from the passenger side of the engine and behind the car. I take it this is a WHOLE new issue I have to deal with.. until now all my testing was in the driveway... not under power or on the road.


Thoughts?
 
I should add... Ive been trying to track down this knocking....its random.. really loud at times.. and lighter at others. I used my automotive stethoscope to try and trace down the sound... I was all over the engine. didn't find it the noise..everything was sounding as it should.. UNTIL.. I placed it on the bottom of the exhaust manifold (right at the flange where it bolts up) on the passenger side.. I found a distinct sound.. kept tracing it down the exhaust pipes... I was called into breakfast and didn't finish (then went to work). Since Im working with the old exhaust system from the PO, and it is a bit of a mess as the car was when I found it. I'm thinking I have either rocks in some of the sheilding or the entire exhaust is hitting at some point on the car. given the moving around of the engine.....I can see why the sound might be there.

again.. thoughts?
 
a loose connection on a muffler, exhaust hanger or loose heat shield,broken valve spring, badly burn rocker ball, a rocker with the slot touching the rocker stud, exhaust leaks , the exhaust system, touching the cars frame, on the catalytic converter,or muffler, worn u-joints, rocks caught in the heat shield, a loose flex plate or bell housing or worn pilot bearing can cause noise in the drive train, or it might be that, if you have an older CATALYTIC CONVERTER, its rather common for the core to break up and partly clog the exhaust.
while it may not be your issue its smart to be aware if the potential problem and check it out.

bustedspringh4.jpg

bcvs1.jpg



catcore.jpg


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caty1.jpg

caty21.jpg

caty3.jpg

caty4.jpg

I got these pictures off the internet but its a fairly common issue too have several chunks of melted CAT come loose ,we found several chunks restricting the exhaust catalytic converter core and exhaust pipes in several corvettes where it transitioned from 3" down to 2.5" diam.
 
The pre catalytic converters are possible broken apart inside.
Debris now blocking the inlet of the main center catalytic converter.
 
Lol. Grumpy had exact same thoughts.
Beat me posting.
 
UPDATE: I've finally tracked down what the rattle noise was... : first off, it sounded like the bottom end of the engine was knocking.. badly, yet at random times. It turns out, I either have rocks in the exhaust on the passenger side (within the first set of silencers) or whatever is in there that's designed to deal with the gases has come loose and is rattling around in there. I did remove the heat shield from the same side, it was full of rocks that were also causing the similar sound.

If anyone knows of a good replacement for the exhaust from the cyl heads to the cat... I'm listening....

Im now tackling the rough idle, I purchased a new cap (with brass contacts) and rotor. I'll put it in time and see what comes of it.
 
Yet another update:

The rough idle seems to be the following: Cyl 1 and cyl.. (second from the back on the passenger side...I don't remember the number off hand), when I remove the injector plug from the injectors, engine idle does not change (as it does with all the rest), I did an ohms test.. each had 17.3 -+.2 however... when I i decided to plug noids into each suspected spot. The engine idle smoothed out a bit and raised a bit. Yes the noid lights were working, you can see the pulses (they blink brighter as the engine revs BTW). If both noids are plugged in the engine idles constant...and sounds the best ive heard yet (however feel like it should be better). I went and found the old injectors from the old motor...ohmed them out.. found the good ones then started to plug things in. Heres what i found: Even though the 6 injectors i ohmed out were within acceptable parameter (16s-17s) only 2 would allow the engine to idle as it did with the noids plugged in. The other 4 caused the same condition...rougher idle..stumbling. I was sure to listen/feel for those 2 working injectors to click when they were plugged in. Here is my question.. is this a grounding issue? How is it I have 8 injectors and 2 are bad out of the box? Im sure it can happen, but what are the odds? Today i'm going to install the 2 injectors and see if I cant get the motor work work as it should. I did drive the car last night about 20-30 miles... at lower RPMs you could tell the engine was not performing as it should.. lopping or dragging a cyl.. or 2.

ANY thoughts? this seems odd to me.
 
second cylinder from the back on pass side should be #6
firingorder.gif

CHECK ALL YOUR FUSES WITH A MULTI METER
fuse_box.jpg

try swapping the installed location of the two suspected too be defective injectors with two that seem to be functioning to see if its the location, or the injectors as a first step,in isolating the cause of your problem.
if the problem follows the injectors that are moved, its the injectors, if the problem stays at the location, that was previously having the problem,and the injectors work at the new location, you know its not the injectors but the older location injector connections or a mechanical issue with the cylinders where they were previously installed.
 
Update: OK... Ive made significant progress. I forgot to mention that my last post I talked about 6 other injectors, I was testing them not installed, yet plugged into the injector wiring harness (basically the 2 suspected broke ones were still physically seated in their position, i was plugging in test injectors to see what would happen). I ended up installing the 2 injectors that seemed to remedy the problem...and guess what.. as they were installed with fuel going thru them.. BAM! a VERY responsive engine came to life. It was also incredibly easy to start, maybe a revolution then it fired up.

NOW... Im still finding an occasionally stubble or loop/missing, however nothing like before. I took it on a test drive and did a WOT test.. huummm... VERY NICE (but I want more). :) Im now wondering if the 2 new injectors might be somewhat clogged, hence causing the occasional miss. Now true to Grumpy's suggestion.. Ive tested instead of just randomly replacing parts.

Question for you Grumpy, Whats the best timing for a GM 350? I believe im at 6 BTC right now ( I think).

OH... and an update on that CLANKING noise.. that I was fearing was the bottom end of a newer engine coming apart... Im farily sure it what you and others mentioned, parts of the preconverter coming apart and clanking around the exhaust system. Any thoughts on how to fix that on a budget? Ive been looking at cat back systems (flowmaster), however not only are they $400-$600, however they dont seem to sell the front pre converters. Anyone have thoughts on that one?

THANKS for all the help and guildence, HIGHLY appreciated and helped with a 24 month project!
 
the truth is timing required will generally be unique to each engine , to some degree but generally you could start at 6 deg btdc and get a timing tape installed on the damper perimeter and verify TDC on the damper and timing tab reflect reality, then verify the advance is consistent, with the rpm, generally stopping at about 36 degees-37 degrees by a\bout 3200rpm

as to the stumble, Id suggest pulling trouble codes, (pay attention if it says the 02 sensors or heat sensors or any sensor for that mater is defective) and adding two different brands of injector cleaner to a full tank of gas, changing your fuel and air filter, and getting a new distributor cap and rotor if yours is old before proceeding

reading thru these links and sub links will help

viewtopic.php?f=70&t=967

viewtopic.php?f=70&t=1015

viewtopic.php?f=70&t=4683

viewtopic.php?f=70&t=875
 
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