Hi guys, Im new here. I bought my 1st Z28 this summer.

Im hoping someone can point me into the right direction with my problem. I have a xtremely modded 95, and it runs great on the rode/down the strip. But my problem is the thing floods bad. I replaced the plug and got Msd wires, I had the injectors cleaned and tested. Funny this is it doesn't throw a code.
I bought the car and it had this flooding issue, I have replaced the map, tps sensors, cleaned the maf. I finally hooked it up to my pc using free scan, and the only thing I noticed is my knock count was like 10,000. It doesnt have a main of a rod knock that I can hear, and it hold great oil pressure.....Anyone got any ideas?

Oh, I took the o2 sensors out and took a torch and heated them to try and clean them also.

Thanks!

 

you cleaned your O2s with a torch??they are probably junk now...Pull the vacuum line off of FPR and check to see if there is fuel in the line.

 

What is FPR? Fuel Pump Reg?
I was told to use a torch to burn the build up off the O2 sensors, but not to heat them too much. But I have no ses codes.
I checked the vacumm hose and there wasnt any gas. But I noticed, at idle my pressure is at 30lbs.....I know thats low but even when I turn on the 2nd pump for the nos, it doesnt move. When I unplug the vaccum hose the pressure bumps up to 35lbs. I adjusted the fuel pressure up to 40 and it completely flooded out. So I assume the fuel pressure being set at 30 is part of the tune. Or can this be a sign of a bad regulator?
Thanks.

 

Has it always run rich? If so, what size injectors are you running? Was the PCM tuned for those injectors?

"Knock Count" doesn't have anything to do with a knocking rod or main. It's a calculated measure indicating operating conditions that MIGHT cause detonation (spark knock). It is normal for the field to increment upwards every time you start the engine. Hence, the actual number in the knock count field is not important. What is important is whether it is continuing to increase as you drive the car. You will also find that it increments to the largest number that fits in the binary field, resets to "0" and starts incrementing all over again. Unless its incrementing as you drive, and accompanied by knock retard, it is nothing to be concerned with.

You won't get a code for running rich if the cause of running rich is faulty feedback from the O2 sensors. If the sensors are inaccurate, if there is an exhaust leak before the O2 sensors, or if you have excessive misfires, the long term fuel corrections will start to increase well above 128, to correct what the PCM thinks is a lean condition. But it's not really lean, so the PCM ends up adding fuel the engine doesn't need.

Since you have FreeScan, what are the long terms fuel corrections in cells 01 through 16?

 

i will post my screen shot of free scan tonight when i get home from work. I have no exhaust leak that i can hear. it has Accel 36lbs, and its tuned for it. i left the fpr vaccum hose unplugged today and drove it around the block. it ran fine...spun up to 8000 a couple of times with no problems. it seemed not to flood so bad at idle....finally it settled in at a 900 rpm idle and threw a code. it was low pressure map sensor. I replaced it also today again and if it idles down too much it will throw that code and i can barely rev it and it goes out...lol. Im just trying to get the loading up so much down some, it dosent load enough to flood out but it will smoke and my plugs will be black. from launch to the upper rpms its fine...of course with all the gas flow. lol.

i do remember that the timing wasnt retarded any from the knock count and the timing is set to 23* and fuel trim is at 16...what ever that is.
and i cant remember exactally but it was something with the O2 reading, it was 149mvl or mlv or something like that...but both were reading that the last scan i did.

 

Why not post a complete FreeScan log on an FTP site, so we can take a look at it. A single frame of data - particularly the O2 sensor millivolts, or mV - is not very useful.

The O2 sensors should be rapidly cycling back and forth between 100mV or lower and up to more than 900mV. You can't tell they are cycling from looking at a single screen shot. It would be very unusual for both left and right banks to be identical, since each bank of the engine is controlled independantly with regard to A/F ratio.

Cell 16 is the long term fuel correction cell used for idle. The important thing is what are the long term fuel corrections (LTFT or BLM) for that cell, both left and right banks?

Are you sure the MAP sensor harness connector isn't crumbling from old age, and providing intermittent contact? Not an unusal problem.

 

I was mistaken, I used datamaster. I recorded it. He is the qiuck run down;
MAP KPa= 72.0

Fuel trim Cell= 16

LTerm Counts= 128 128

STerm Count= 128 128

BPW mS = 3.39 3.37

INJ DC = 2.7 2.7

O2 mV = 462 235

AFGS = 12.95

TPS % = 00.00

TPS VOLTS = 0.76


Thats just a snapshot if it. I have recorder live data, for about 2 min

I observed the data as it ran tonight and I notice that one O2 sensor stayed in the 500mv rangeand the other one stayed around 250mv, all this at idle.

 

Limited value in that frame. Was it in open loop (probably, given the 128 long and short terms) or closed loop? A static O2 sensor reading in closed loop is a problem. I dead O2 sensor will hang up at about 450mV.

Again, if you want help, you have to upload the Datamaster log so I can download it and see what's wrong.

 

Is there a certain place i should upload it at?

oh it was open loop.

 

Go to the "Computer Diagnostics and Tuning" forum, and look for threads with titles like "can someone look at my data log?". You can see what ftp sites others have used. I've downloaded data logs from many sites, but I have no reason to upload. Here's a typical thread, with a site that worked fine:

https://www.camaroz28.com/forums/com...atalog-849029/

 

I uploaded them to 4share.com and I post it in the place you said. here are the 2 links tho.

1995z28_eng2.uni - 4shared.com - online file sharing and storage - download
1995z28_eng_1.uni - 4shared.com - online file sharing and storage - download

I found something today. It did not have a thermstat in it. I bought one and it changed the way the car ran.

cold start idles at 1000-1200. still rich.
warms up to operating temp, it idles down around 800-900, and map code again. holds there. I rev alittle and ses lite goes out, soon as I let off the gas it idles back to 800-900 and ses lite is back on....oh still rich. I played with the map sensor plug, and I noticed with the car idling, I can unplug it and it makes no difference.

 

Did you get the correct t'stat, specifically for an LT1 engine? You can't use the one from a Gen 1 small block Chevy.

http://shbox.com/1/tstat.jpg

It's normal for it to idle higher on cold start. There's a table in the PCM that raises the idle temp based on coolant temp. Additionally, the stock, warm idle for a manual trans LT1 is 800rpm. On top of that the stock tach typically reads 100-200 higher than actual RPM. And, with any sort of more aggressive cam it wouldn't be unusual for the tuner to bump the idle speed. What the tuner did to idle will become apparent when I download the .uni file and look at the data.

What is the exact code for the MAP sensor? If you have an aggressive cam, the idle MAP may be higher than the threshold that sets a code for high MAP volts/high MAP/low vacuum.

I'll try the download.

 

it has a radical cam. I cant remember the # of the code...just its low vaccum map. should it make a difference if i unplug it? i have all aftermarket gauges and all...the egr was deleted....guy i got it from said it was mildly tuned so if you wanted to drive it alittle on the street you could. he had videos of it running mid 11's before using nos.

Since i was messing around with it today a had it running after i drove it about 1/4 down the rd and i raised the hood and i smelles gas. So i put the vaccum hose back on the fpr and the smell went away...that norm? i saw no gas coming out of it tho.

thanks for all your help man!!

 

Oh sry yeah i got the correct one for a lt1

 

The date on the files indicate 2/2/12. Would appear to be BEFORE you replaced the t'stat. It isn't getting hot enough to go into closed loop.

You have DTC 33, high MAP. MAP is 80-83kPA at idle, vs a barometer of 100kPa. You either have a large cam, a not-so-hot-tune, or a valve adjustment problem, etc.

Run a log with the t'stat in it. It should be running around 180*F.