Car is surging and idleing poorly- REALLY stumped

S

SilverBullet00

New Member
Jul 5, 2004
1,150
0
0
Wichita, KS
#1
Well I finally got my head gaskets replaced and my cams installed. The only problem is the car idles a little high and I have a surging problem. To start off after I got the car all back together after the install the car fired right up. I revved the motor for 10-15 min between 1500 and 3000 rpm,s to get oil to the cams. After that I let the car idle for about 10 minues- here it idled at 900rpm and sounded AWESOME!

The second time starting it up it wouldnt start. I tried a couple things and then finally gave it some gas and it would turn over, only now it was idleing at 1200rpm! I took the car for a drive and when I pulled up to the first stop sign, as soon as I pushed in the clutch, the car shot up to 2000rpms! And it doesnt drop untill I sit there for about 5-8 seconds. VERY annoying.

Here is what I have tested so far:

1. cant find any vacuum leaks
2. Passanger side 02 sensor got burned up, fixed the wiring
3. Cannot get a reading from bank 2 02 sensor with the xcal2 dataloger
4. Blown #8 fuse under the dash for engine control
5. Cleaned IAC housing
6. Unhooked the battery after every step
7. NO trouble codes

After all of this the car idles at a stand still a little better and doesnt die, but it still surges. The tune is from MPH and the cam install was done perfectly, everything degreed perfectly. Where do I go from here? Im thinking about just taking it to the dealership and saying FIX IT!!!

Thanks for any and all suggestions, thanks!
 
#5
yes they are deffinetely the front O2 sensors- in the program it even says FRONT so its pretty fool proof. Long term fuel trim is around 1 at all times for both banks. After the car is good and warm each side fluctuates a bit and can do anywhere from 1-.996.
1, according to sct, means 14.64 a/f ratio.
 
#6
SilverBullet00 said:
yes they are deffinetely the front O2 sensors- in the program it even says FRONT so its pretty fool proof. Long term fuel trim is around 1 at all times for both banks. After the car is good and warm each side fluctuates a bit and can do anywhere from 1-.996.
1, according to sct, means 14.64 a/f ratio.
Click to expand...


you software might read different than ours.

Long term fuel trims should be in the form of anywhere from -25 to +25..

what it means is how much the pcm is adding or subtracting to the mixture. a +25 on both banks tells me that the car is very lean and could have a vac leak, where one side reading lean could be a misfire
 
#7
Here is SCT's explanation. Let me know what you think. If I cant get it settled by thursday Im just going to take it into the dealership. Also, if the 02 sensor is bad, I have heard many people say you must use a motorcraft replacement, not a bosch...what do you think? I was thinking bosch probably made them for ford?


Please note that trim values are expressed as 1.0 being stoichiometric (14.64). For short term trim values a value
of greater than one means the engine is running rich and the ECU is removing fuel, e.g. a short term trim value
of 1.10 means that the engine is 10% rich and you’d need to multiply the MAF curve in that area by 0.90. A
trim value of 0.90 means that the engine is running too lean and the ECU is adding fuel. Now the confusing part
– for long term trims it is just the opposite and the display is different as well. For long term trims you need to
add 0.5 to the reading you see – if you see a long term trim of 0.53 displayed, then the actual value is (0.5 +
0.53) = 1.03. Long term fuel trims are displayed inversely to the short term trims – a value of 1.10 means the
engine is running too lean and the ECU is adding fuel, a value of 0.90 means the engine is running too rich and
the ECU is pulling fuel.
 
#9
The car also bucks and jerks a little bit around 1500rpms when driving. Also when driving in 1rst and 2nd gear the throttle pushes the car- I dont even have to have my foot on the gas to accelerate. I will see if I can get the datalogging program to work tomorrow.

By the way if I take it to the dealership will they give me crap about my exhaust and cams?
 
#10
Ok, I went out any datalogged some more today. I found that when I remove my TPS sensor the car remains the same... should this be? It has no affect at all. Also, is there a way I can post this spreadsheet? From what SCT says I am running rich on bank 1 according to the Short trim fuel curve and the long curve has me running rich.... what is going on?

Also, both oxygen sensors are working now!
 
#12
Sounds like your tune is off. It may be that your MAF isn't calibrated properly to your injectors. Start the car and let it idle. While the car is running unplug your MAF, if should stall the car. What does it do while you are driving? Does it run poorly? Depending on what you did i would get a full dyno tune not just a mail order. Dyno tune is always the safest way. A mail order tune is tuned to the shops conditions, not to where you actually are. If you elevation and humidity are totally different it could cause your car to run rich or lean.
 
#14
Well the computer is deffinetely NOT learning it. I have been driving it as much as humanly possible. And there is no place around here to get a dyno tune- thats why I went with the mail order tune.

BUT right now its at the dealership getting checked out, after changing the head gaskets and messing with this for a week I am tired- also working 50 hours a week is killing me.. I will post up any progress...

thanks for the help guys!
 
#19
nope, I didnt touch the TB. I know its been awhile since I last reported but I have been on vacation.

Anyways from further diagnoses I have found that bank one is running lean, up to 18% according the the xcal2 datalogger. At first I thought maybe a timing chain slipped but then I remembered after I turned it over the motor for the first time and reved it for 15-20 min and then let it idle, it idled PERFECT. Since then it hasnt, is it still possible a chian could slip? How can I thoroughly (sp?) check for a vacuum leak?
 
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