Need help to repair rough idlewhen cold and engind codes that keep coming back P0170 and P1188

Tiny
TEXASDAWG2003
  • 1998 BMW Z3
  • 15,500 MILES

Working on a 1998 bmw z3 roadster with a2.8 engine and the check engine light comes on the codes are p0170 and P1188, when the car starts up cold it runs rough and when it goes into closed loop it smothes out and runs fine. The intake and vac lines were smoke tested and leakes repaired. New plugs, fuel filter and ccvv/oil seperator was replaced, idle air valve cleaned, air felter cleaned. Data on a scane tool first time the front o2 sensor read 0% at.92volts and o2 sensir after the cat read 99.2 at.96 volt, replaced the front o2 sencer and rechecked date and the voltage on the front o2 sensor started to go up and down as needed.79 volt to.98 volts and read 25% rear sencer stayed at 99.2 % the car still runs rough at cold idle. Maf was changed not differance. Air control valve was changed no differance checked fuel pressure with 3 different gauges fuel pressure was 44 to 51 PSI depending on what gauge was used. Tps reads 17 to 18 on at idle. With the reading of the o2 sensors is the fuel pump not putting out enough pressure. The car at times will have blacke smoke. Your help or answer on this matter will be very helpfull. If it is the pump how do you get to it.

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Monday, June 18th, 2012 AT 4:27 PM

23 Replies

Tiny
TEXASDAWG2003
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If more information please ask I well get information needed to repair car as needed. To repair codes and cold starts

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Monday, June 18th, 2012 AT 4:33 PM
Tiny
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Both codes are related to long term tirms out of range.

Possible causes are vacuum leaks, low fuel pressure, pcv system, mass air flow sensor. All these need to be verifed by a shop with a scan tool that can monitor these systems.

Roy

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Tuesday, June 19th, 2012 AT 12:32 AM
Tiny
TEXASDAWG2003
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The intake was smoke tested for leaks. Ccvv was replaced, mas air flow was replaced and no differance what should fuel presssure be and numbers do you need to see from the monitor

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Tuesday, June 19th, 2012 AT 2:56 PM
Tiny
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Was the smoke test done cold when the issue occured. When it gets hot and runs better, the seals expand and seal off vacuum leaks.

Roy

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Tuesday, June 19th, 2012 AT 10:34 PM
Tiny
TEXASDAWG2003
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The test was done cold I did another test I took off the pcv hose and pluged it and it ran fine cold and worm is there an air reductucting valve in the valvle cover or tubing. Someone else changed the valve cover gasket so I dont know if there is one or not it did not run rough or set the pending codes like it did before I pluted the line is the spark plug tube seals leaking+

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Friday, June 22nd, 2012 AT 1:48 AM
Tiny
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If you leave it plugged, it will not allow the crankcase pressure to vent and you will create oil leaks. Just replace the valve.

Roy

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Friday, June 22nd, 2012 AT 2:37 AM
Tiny
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Ccv has already been replaced it was doing the same thing before it was replaced it olny idles rough when cold as soon as it goes into cloased loop it runs fine

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Friday, June 22nd, 2012 AT 4:03 PM
Tiny
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I hear you but I still feel you have vacuum issues when cold and they seal when warm. The people working on the car, are they bmw techs?

Roy

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Saturday, June 23rd, 2012 AT 12:30 AM
Tiny
TEXASDAWG2003
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Spark plug tube seals and valve cover was replaced again one the first start it did not run rough on start I will see it it runs better on next start it looks like was not holding vacume in eng what should the o2's read while runing

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Saturday, June 23rd, 2012 AT 4:31 PM
Tiny
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You need a scan tool to read this as they are fuel ratio sensors. The trims are important as they should be under 5%

Roy

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Saturday, June 23rd, 2012 AT 5:41 PM
Tiny
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Thanks for all the answers if. The 02's suppose to read under 5% then if they are at 25% on per and 99.2 % ON POST THAT MEANS IT STILL RUNNING LEAN HOW LOW WILL THE FUEL PRESSURE GET ON THIS CAR BEFORE IT QUITS RUNNING IT HAS 42 PSI WITH THE 4 TH NEW GAUGE I WOULD GUESS THIS IS TO LOW FOR THE O2 READING THE VALVE COVER WAS THE LAST INTAKE LEAK I FOUND

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Sunday, June 24th, 2012 AT 1:02 AM
Tiny
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Around 20 lbs

vacuum leaks, pcv, mass air flow are some of the reasons for the trims the way they are.

Roy

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Sunday, June 24th, 2012 AT 3:25 AM
Tiny
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Master6371 all that was changed hoses and what should the fuel pressure be and if it is low will it set codes and the o2 reading

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Sunday, June 24th, 2012 AT 4:24 PM
Tiny
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Fuel pressure 40-48 lbs

if it is low, it will set a 174 code for lean.

O2 sensor will show trims at +18-20%

Roy

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Monday, June 25th, 2012 AT 1:54 AM
Tiny
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Front and rear 02 will read this or just the front when I pinch off the fuel return line the fuel pressure does not change the rear o2 rears 99.2% and the front reads 25% this does mean that the comp is trying to add Fuel?

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Tuesday, June 26th, 2012 AT 12:59 AM
Tiny
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How are you reading this? What scan tool are you using?

Roy

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Tuesday, June 26th, 2012 AT 10:46 AM
Tiny
TEXASDAWG2003
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Two different scanners snap on and an EVO.
Do the front and rear o2 reads the same
when checking fuel pressure its in the very low 40s and when pinching off the fuel return line pressure does not change is this why it 02 is reading high and is the computer trying to add fuel to the system

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Tuesday, June 26th, 2012 AT 12:46 PM
Tiny
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No, front o2 varies high to low and the rear stays close to constant.

Fuel pressure looks good.

I still think you have other issues with either vacuum leaks and what kind of mass air flow did you use?

Roy

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Tuesday, June 26th, 2012 AT 11:27 PM
Tiny
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The valve cover some bmw dealer put on was not sealing I found this by plugging the pvc tube and the engine idled perfect I smoked the valve cover and the spark plug seals were leaking and the rear of head were the cam slotts are replace all the seals and gasket and runs good I was but hard to start or slow to start the fuel pressure on the gauge stated 42 but acted sluggish replaced pump pressure went to 46 and 55 at max the car now starts as soon as I turn the key and idles perfect going to test drive couple of times to see if codes come back and all the parts are the same bosh number that is on the bmw/bosh parts most came from bmw

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Wednesday, June 27th, 2012 AT 2:21 AM
Tiny
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Vacuum leaks are the most common issues with the trims codes you had.

Good luck

Roy

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Wednesday, June 27th, 2012 AT 2:27 AM

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