 New Topic
|  Reply to Topic
| Bookmark Topic
|  Printer Friendly
|
| Author |
 Topic  |
|
|
matthewt
Grease Monkey
Status:
offline
54 Posts
|
 Posted - Oct 31 2009 : 14:51:06
|
|
Hey guys!! Haven't posted on here in a while but been steadily at work on the 745. INjectors were just ultrasonically cleaned, new intake gaskets and new intake rubber. Removed Johnson box, a big improvement!! Smoother idle and no more hesitation off idle when warm. The problem now is under full throttle and boost, it is cutting out. It did not do this prior to removal of JB.Wiring is correct back to stock, fuel psi is 37 pulling 17" vacuum at warm idle, just dialed in TPS though it wasn't terribly far out of adjustment. With vacuum/boost gauge installed, runs fine to 3psi, as soon as I stomp on it, above 3psi the gauge goes NUTS! It bounces all over the range until I back off the pedal. Any thoughts anyone else had this problem after JB removal?? Coming up on a year now since I've owned it, and considering the condition it was in when I drove it home(small miracle), I am very pleased with how it is now!! THanks for any help, guys!!
|
|
|
scottie
System Administrator
Status:
offline
3743 Posts
|
 Posted - Nov 01 2009 : 17:45:06
|
| Measure resistance on wire from temp sender to ECU. I think it is pin 13, but don't quote me on that. I bet this wire is all fubbed up. Check for and remove any resistor in the bootie near the sensor. |
Scottie Sharpe
San Jose CA
Discussion Board SYSOP
88 Dinan M5
1968 2002
1987 BMW K100RT
1982 Yamaha Seca 650
1995 Mitsubishi Montero SR
FOLLOW ME ON TWITTER
My Profile
 |
 |
|
|
matthewt
Grease Monkey
Status:
offline
54 Posts
|
Posted - Nov 01 2009 : 18:37:59
|
| Thanks Scottie, that was going to be the next thing I check. I looked under the boot, though, and it's not there, but I seem to recall someone else on the board finding theirs several inches from the plug, so I'll keep looking. Other than the cutting out, yanking the JB is one of the best things I've done to the car yet, thanks to the forum!! |
|
|
|
scottie
System Administrator
Status:
offline
3743 Posts
|
Posted - Nov 01 2009 : 20:38:36
|
| That wire is cut and spliced into teh JB wiring. Ensure that you put it back to stock. |
Scottie Sharpe
San Jose CA
Discussion Board SYSOP
88 Dinan M5
1968 2002
1987 BMW K100RT
1982 Yamaha Seca 650
1995 Mitsubishi Montero SR
FOLLOW ME ON TWITTER
My Profile
|
|
|
|
Hit Man X
Over 745 Posts!
Status:
offline
1421 Posts
|
Posted - Nov 02 2009 : 01:03:22
|
quote:
Originally posted by matthewt
Hey guys!! Haven't posted on here in a while but been steadily at work on the 745. INjectors were just ultrasonically cleaned, new intake gaskets and new intake rubber. Removed Johnson box, a big improvement!! Smoother idle and no more hesitation off idle when warm. The problem now is under full throttle and boost, it is cutting out. It did not do this prior to removal of JB.Wiring is correct back to stock, fuel psi is 37 pulling 17" vacuum at warm idle, just dialed in TPS though it wasn't terribly far out of adjustment. With vacuum/boost gauge installed, runs fine to 3psi, as soon as I stomp on it, above 3psi the gauge goes NUTS! It bounces all over the range until I back off the pedal. Any thoughts anyone else had this problem after JB removal?? Coming up on a year now since I've owned it, and considering the condition it was in when I drove it home(small miracle), I am very pleased with how it is now!! THanks for any help, guys!!
What does the fuel pressure do at full throttle?
Do you have a wideband on the car? Need to see 11.8-12:1 at hot idle.
Cutting out could be many things, usually car is leaning out.
Not exactly sure how that J-box manipulated the signals back to the Motronic so if I was in your shoes, I would just start at square one. Test the sensor Scottie pointed out... my '83 would just DIE it was so bad. Look for bad/loose grounds. Check oxygen readouts at idle (my AEM gauge setup works great and do not have to do the BS calibration like you do with the Innovate brand)
What spark plugs? NGK BP5ES seem to work fine here (or it is the BP5EFS, let me check my notes tomorrow... one I use in my 300SEL ha).
Magnetic valve hooked up properly? Bottom to suction tube (that AFM hooks to), furthest out to the wastegate, inner to the compressor housing.
Come to think of it, I too had a resistor on my Ljet up by the temp sender too. This car was really dicked with when Federalized... EGR installed, AIR injection put on (HUGE lag as the manifold does not flow properly), O2 sensor to nothing, etc |
This is my sig... 
THREE 745i! 83/84/85  |
|
|
|
Mike_745
Starting Member
Status:
offline
7 Posts
|
Posted - Nov 02 2009 : 13:36:08
|
| Mine used to cut out under boost - it turned out to be a faulty performance chip. Replacing it took 15 mins and it ran beautifully. |
1984 745i/5-speed
2002 330i -wife's car |
|
|
|
matthewt
Grease Monkey
Status:
offline
54 Posts
|
Posted - Nov 03 2009 : 17:36:18
|
| Well, checked resistance tonite in collant sensor wires and no resistor so looks like next step is to check/tune/adjust AFM...wires are clean to the DME. I understand that you really need a wideband sensor and a/f gauge, but is there a voltage value I should be seeing at the AFM for idle and WOT?? Right now it's not going anywhere til I resolve the radiator issue, and THAT is going to depend on whether I can find used or buy new...used, be on the road fairly soon; new, won't be on the road for a while:) |
|
|
|
scottie
System Administrator
Status:
offline
3743 Posts
|
Posted - Nov 04 2009 : 11:42:28
|
| Your temp resistor may be bad. Search this site for resistance values. You can test it by dunking it in water on the stove. Don't let the wife catch you! |
Scottie Sharpe
San Jose CA
Discussion Board SYSOP
88 Dinan M5
1968 2002
1987 BMW K100RT
1982 Yamaha Seca 650
1995 Mitsubishi Montero SR
FOLLOW ME ON TWITTER
My Profile
|
|
|
|
scottie
System Administrator
Status:
offline
3743 Posts
|
Posted - Nov 04 2009 : 11:46:30
|
| Your temp resistor may be bad. Search this site for resistance values. You can test it by dunking it in water on the stove. Don't let the wife catch you! |
Scottie Sharpe
San Jose CA
Discussion Board SYSOP
88 Dinan M5
1968 2002
1987 BMW K100RT
1982 Yamaha Seca 650
1995 Mitsubishi Montero SR
FOLLOW ME ON TWITTER
My Profile
|
|
|
|
matthewt
Grease Monkey
Status:
offline
54 Posts
|
Posted - Nov 04 2009 : 18:13:33
|
| Already installed brand new coolant temp sensor. The car will probably be low priority in general now til Feb. as I can't safely test any mods/adjustments with the compromised radiator. Thanks for the help all, if anything else comes to mind or if one of you has a spare 745 rad out there, you can email me at mkrumal@yahoo.com. Cheers!! |
|
|
|
Hit Man X
Over 745 Posts!
Status:
offline
1421 Posts
|
 Posted - Nov 23 2009 : 15:55:05
|
More stuff to view:
is the magnetic valve good? did you make the correct 6psi with the Jbox installed?
The AFM could simply be very lean, my two cars that run were like this... I mean multiple notches incorrect (3-6!)! Never trust previous owners unless they are members here.
Issue simply could be an unrelated part has died.  |
This is my sig...
THREE 745i! 83/84/85 |
|
|
| |
Topic |
|
|
New Topic
| Reply to Topic
| Bookmark Topic
| Printer Friendly
|
cutting out under boost