Troubleshooting a miss, etc

[ULYCYC]

That was my next question.  If you flip the green and yellow wire to make it run with plug wires wrong, you could have issues

[Steve Wood]

Okay, Keith, let's start over from ground zero.

Ed and I spend too much time talking about what might be the problem and each time, we don't know enuf to have a good argument

First, let's start at the beginning.  You first converted the car from the hot air ecm to the 86/87 ecm as I recall.  What all did you change to do this and where did you get the instructions?  I remember you talking about it a couple of years ago.  You said you had a new harness.  Which harness is this?

What maf are you using now?  At one time  you were using one I gave you but I think it died.  Are you using a rebuilt factory maf, or did you go to a Translator/LS or LT maf?

Then more recently, you converted the car to being intercooled.  Did you get rid of the hot air intake set up  with the turbo at the back and replace it with the intake from and intercooled set up along with the headers to mount the turbo at the front of the engine?

Are you running an alky chip or a regular chip?

My guess is that you have at least two problems, and maybe more.  So far we have been concentrating on the cam sensor which is not behaving properly, but from the symptoms we started out with, this may be one problem which could be a module or maybe wiring if something was wrong in the original conversion.

On the other hand, the miss at part throttle, low boost, that changed when we moved the alky turn on point upward....that could be something to do with the cam senor, or maybe it is not.  If you are using a rebuilt factory maf, it could be a wrongly calibrated maf that is not giving the right air flow numbers at part throttle, or maybe a fuel pump that is losing pressure as the boost comes on.  Having the alky start early could possibly cover it up by covering up the low fuel pressure of a bad pump, or the wrong airflow numbers from a badly calibrated maf.

Given what we don't know, maybe we should start by looking at the basics before we start chasing the geese.

With the car warmed up to 165 degs, or so..   let it idle and give us all the scanmaster numbers.  Also, give us the vacuum at idle...both in park and in drive.

Put a fuel pressure gauge on it and tell us what the pressure is at wot thottle in third along with the boost you are seeing...and, of course, what the pressure was at idle with the hose off the regulator so we know if things are working, or not.

[$1987 GN$]

Just a pic of the wires.

AJ___

[gbsean]

also do you have a known good cam sensor...John had a bad batch at one time...my car car would start run and then shut down...with johns new cap..I swapped in my old one and it was fine

[TurboCajun]

ok I have the 85 block, 85 turbo upgraded, and everything else is 87---- coil, module, intake, headers, etc.. I do have translator and i think its the impala ss MAF. I have front mount intercooler, razors alky, TT alky chip. ****** now today Steve I started the car and unpluged the cam sensor it started to idle a lil rough but when I give it throttle it seems to be fine, which is what John said that It would load up a lil at idle because the fuel is puddling on the cyclinder that is not firing. so that leaves me to think that its not the sensor. I dont know if this is a miss or just a fuel issue, the only think that makes me thinks its a miss is that when i am driving and the trans goes into OD I can feel the bump like a miss. I havent had time to pick up a part for my fuel pressure gauge yet, but I will soon.  I did have a chance to check all my ground and they are all good clean and tight, I added a 12 gauge wire from the block to one of the screws on the module just from insurance. Please note that this issue is not is happening about two to three times in a minute and is not a constant miss .

[Steve Wood]

strange...I will unplug my car with 75# injectors tomorrow and see how long it takes it to act up...never saw it do it, but, I have not let it idle very long.  Ed wondered about it loading up earlier.

But something seems to have changed.  Until now, you said it idled very rough and the car could not be driven as it seemed to be running on three cylinders if you tried.  So, what changed?

[TurboCajun]

it was a cold start it usually run decent for a 1-2 minutes before it starts to acked up on a cold start

[Steve Wood]

so, I am confused....yo u said it would run very badly, and more recently it would actually kill the engine.  I am trying to find out if there has been any change from where it is right now, and how it has been since we started chasing the problem.  At the moment, it seems close to normal as opposed to running very badly in the past.

We have spent several days trying to find out why it would not run when unplugged, and tonight, it sounds like it is not really that bad.  Is there a change? 

Further, did you drive the car?  Is it still cutting out an missing when the boost starts to come up under part throttle?

[ULYCYC]

Something I ran across a few times.  I want you to try something.  Start the car then disconnect the fuel pump. Let the car run dry and stall.  Remove the schrader valve from the fuel rail. Hook up a temp hose and hold a clear bottle to catch the fuel. Hook up the fuel pump for a second and then disconnect when you get about a pint of fuel. Now look and see after the fuel settles if it's full of metal flakes and rust.

Also did you buy the injectors or they came with the intake? Post the numbers that are on the injectors

[TurboCajun]

so, I am confused....yo u said it would run very badly, and more recently it would actually kill the engine.  I am trying to find out if there has been any change from where it is right now, and how it has been since we started chasing the problem.  At the moment, it seems close to normal as opposed to running very badly in the past.

We have spent several days trying to find out why it would not run when unplugged, and tonight, it sounds like it is not really that bad.  Is there a change? 

Further, did you drive the car?  Is it still cutting out an missing when the boost starts to come up under part throttle?

Steve when at idle at normal operating temp and the engine is running rough that is when the car shuts off when i unplug the sensor, but on the cold start the engine is idling a lil better and faster so when i unplug it it stays running, at one point when we were moving timing around there was a point where it would not run at all when unplugged.
I did not get to drive the car because of rain yesterday,

[TurboCajun]

Something I ran across a few times.  I want you to try something.  Start the car then disconnect the fuel pump. Let the car run dry and stall.  Remove the schrader valve from the fuel rail. Hook up a temp hose and hold a clear bottle to catch the fuel. Hook up the fuel pump for a second and then disconnect when you get about a pint of fuel. Now look and see after the fuel settles if it's full of metal flakes and rust.

Also did you buy the injectors or they came with the intake? Post the numbers that are on the injectors

these were my injectors some delfi-38

[Steve Wood]

Then, I would guess the car does not idle properly when warmed up even when the cam sensor is plugged in?

That would seem to indicate that the car is too lean in many cases.

So back to square one.  Give us your scantool readings for blms, O2s, and voltage when the car is above 165 degs with the car in drive.  Also give us the vacuum at idle in drive at the same time.

The prior six pages are why five minutes of real time is equal to two weeks of internet time...

[Steve Wood]

Here is a good place to buy a pressure gauge...or just the fitting if that is all you need  http://www.metcomotorsports.com/proddetail.asp?prod=MFP0001

[Steve Wood]

Okay

Two cars

GN-75# injectors, 210 deg roller cam, ported heads--started first time in three months.  Warmed up to 165 degs, unplugged cam sensor, check engine came on, idled for five minutes and never skipped a beat...ran perfectly.

T-50# injectors, stock cam, ported heads....drove it a 100 miles yesterday.  Warmed it up to 167 degs, unplugged cam sensor, check engine lite came on, idled for five minutes and never skipped a beat..ran perfectly

So much on the fuel puddling and loading up the engine theory...in my experience anyway. 

This has been my experience with my cars since 1986.  It corresponds to all others that I have worked on that were running right.  I am guessing that there is a problem some place that is going to take scantool data and fuel pressure data to start with.

If you drive the car with it warm so the O2 sensor is reading correctly, when you stop and let it idle, at that time you should be seeing around 780-800 before the O2 begins to cool down.  BLM's should be very close to 128.

If you don't have fuel pressure gauge, then turn the alky off, lower the boost to 16 psi, and then go wot in third gear while watching the O2s.  They should be around 780 if the fuel pressure is adequate.   It is important to get the alky turned off so we can see what the fuel pump is doing.  Otherwise the alky can make one run seemingly okay even when the pump is weak.

If it will not run properly without alky, you only increase the chance blowing something up if you turn the alky on and turn the boost up....alky does not fix problems, it only gets you deeper over your head if the car does not run right to begin with.

[Steve Wood]

also, give us the vacuum with the car fully warmed up and in drive...if the reading is not steady, describe it