V6 hard to take off when hot

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Mar 6, 2010 | 03:06 PM
  #1  
Hello everyone!

Sorry for my bad english.

I have 1988 (manual 5 speed transmission) camaro with swapped engine from 2.8 to 3.1

Car is hard to take off when hot (engine shakes and trying to stall), but when she is moving no matter with which speed (even 1 km\h) she have no any driverability problems.

When car is in open loop then she taking off good, when in closed loop and hot - bad. When i shout off ignition and let car to cool down she make first take off good, then i drive to first red light and full stop and again horrible take off. like piece of junk

I have this injectors installed (Ford F57E-9F593-A4A ) http://cgi.ebay.com/ebaymotors/6-198...item5639a7645e

seems like these injectors little shorter than original

I have found out that i have vacuum leak where injectors enters intake (lower bottom)

I forgot to check previous injectors for this vacuum leak, but before i have replaced 'em i had same problems with difficult take off

i have no engine codes(except sometimes 24 VSS), have replaced distributor cap, rotor, wires, spark plugs

I have log from WinALDL, please take a look. Maybe i have any problems with some of my sensors? I noticed that i have misadjusted TPS when i release throttle i have -1.2% - 0.7% (0.49V) when i hit throttle pedal i have 77-80% (3.8V)

Also when i hit and release throttle pedal my rpm first drop to 2500rpm from higher, then holds here for 1-2 seconds, then drops to 900(to idle). Is it normal?

again sorry for bad english and thanks for answers

V6 hard to take off when hot-inj.jpg  

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Mar 7, 2010 | 11:17 AM
  #2  
Re: V6 hard to take off when hot
Check the vacuum leak at the injectors. Better yet, find a set of intake gaskets and replace those. Also check for leaks in the air intake between the mass air flow sensor and the throttle body, and at the PCV valve pipe connections.

:edit: Looked at the numbers on the eBay listing. Those injectors are too big for your 3.1. I had some about the same size and they ran like crap also. These MAY work better: http://cgi.ebay.com/ebaymotors/FORD-...Q5fCarQ5fParts

The fuel injectors in the listing you posted are 17 lbs/hr. Stock 3.1 fuel injectors are 15 or somewhere around there. Any GM 3.1 built before 1995 (provided it is a multi-port engine) has the same size injectors. After 1994, when sequential fuel injection came out, that's when GM stepped up to the 18 lb/hr fuel injectors in the 3.1 liter displacement. Someone in that store didn't do their research properly when they created that listing.

Also, your TPS reading is right on where it should be for the engine computer for idle, which is between .45 and .65 VDC.
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Mar 7, 2010 | 11:56 AM
  #3  
Re: V6 hard to take off when hot
Install the correct injectors and change your o2 sensor.. also fix those vacuum leaks and it should be fine.
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Mar 7, 2010 | 12:20 PM
  #4  
Re: V6 hard to take off when hot
Thank you very much, Maverick. My old injetors was like these http://www.fuelinjectorwhse.com/injectors.php?id=MP3014 bostech 7240 17084888
Maybe i'll buy 'em but all of them are remanufactured

I think i'll set them back(my previous) to car and will check for vacuum leaks

Alsо today i have noticed that WinALDL dont set "idle flag" and sometimes set "asynchronous fuel flag"

I was trying to read number on my ECM, but someone of previous owners removed the label. I think it was 1227302
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Mar 7, 2010 | 12:24 PM
  #5  
Re: V6 hard to take off when hot
Quote: Install the correct injectors and change your o2 sensor.. also fix those vacuum leaks and it should be fine.
Thanks.
How did you noticed that O2 is bad?
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Mar 7, 2010 | 02:09 PM
  #6  
Re: V6 hard to take off when hot
2 things. you said it runs bad in closed loop, and since you've got too large of injectors installed it's probably coated in carbon.


If the V6 program in the Fbody is the same as the Jbody then the o2 is ignored at idle. It's probably on the verge of flooding itself at idle in closed loop.



I would also replace your spark plugs, and change your oil. I guarantee it's got fuel in it. Pull the dipstick and smell it. If it smells like gas then you'll know for sure.


I've never used WinALDL, but what are your BLM's at idle? and what does the o2 sensor say?
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Mar 7, 2010 | 03:25 PM
  #7  
Re: V6 hard to take off when hot
Quote: 2 things. you said it runs bad in closed loop, and since you've got too large of injectors installed it's probably coated in carbon.


If the V6 program in the Fbody is the same as the Jbody then the o2 is ignored at idle. It's probably on the verge of flooding itself at idle in closed loop.



I would also replace your spark plugs, and change your oil. I guarantee it's got fuel in it. Pull the dipstick and smell it. If it smells like gas then you'll know for sure.
Yes. More than likely.

Yes to the first part, No to the second.

No.

IF his fuel injectors are actually 17# (I can't find them on the 2 lists I use for injector interchange lookup), they are slightly smaller than the 3.4 fuel injectors I ran for about a year until last spring when I found out they leaked (18.4#). My engine ran rich, but never came close to flooding out at idle and the oil never smelled of gas. :edit: And this was with a bad MAF making things worse.
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Mar 7, 2010 | 03:43 PM
  #8  
Re: V6 hard to take off when hot
blm ~115
O2 varies from 0.150 to 0.900
strange that program see battery voltage as ~4.6 V most of time, some times 11, sometimes 20

sometimes i have "old high gear flag". What is it?
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Mar 7, 2010 | 04:35 PM
  #9  
Re: V6 hard to take off when hot
Quote: Yes. More than likely.

Yes to the first part, No to the second.

No.

IF his fuel injectors are actually 17# (I can't find them on the 2 lists I use for injector interchange lookup), they are slightly smaller than the 3.4 fuel injectors I ran for about a year until last spring when I found out they leaked (18.4#). My engine ran rich, but never came close to flooding out at idle and the oil never smelled of gas. :edit: And this was with a bad MAF making things worse.
aah, yah.. not sure on the MAF tunes. It's probably a little more accurate than the SD.


Idle BLM of 115 isn't too bad, but with the ecm seeing that battery voltage spike around who knows what it's doing with the injector offset tables. I'd check all your grounds and check the system voltage with a meter with the car running, if it's actually bouncing around that bad then your alternator might have a problem.
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Mar 8, 2010 | 09:44 AM
  #10  
Re: V6 hard to take off when hot
But, then, he is running a 2.8 vs my 3.1... Could be worse than I think, but I did run 305 TPI fuel injectors for around a week (now THAT'S CRAZY rich!), and I think the 305 injectors are bigger than the 3.4's. Don't really know if the oil smelled like gas or not, but it didn't flood out at idle. It just ran like real CRAP.
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May 29, 2010 | 01:51 PM
  #11  
Re: V6 hard to take off when hot
I've changed MAF sensor. Now i have code 45 O2 rich
Also my FPR is adjustable, it adjusted to 50PSI at idle for better performance. Maybe I should decrease fuel pressure?

Attachments contain 3 logs, every ends with code 45 and then O2 freeze at 0.850 (+/- 0.02) until i shout down and start again car


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May 29, 2010 | 03:26 PM
  #12  
Re: V6 hard to take off when hot
stock pressure should be 40 -47 at idle.
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May 29, 2010 | 06:51 PM
  #13  
Re: V6 hard to take off when hot
Correction on the above number is that stock fuel pressure is 37-47 PSI running. Should be between about 41 and 51 PSI with the engine stopped (if that makes it easier for you to adjust the fuel pressure with the engine not running). The pressure regulator will take away about 4 PSI with the engine running.

The only time more fuel is needed is with a bigger cam and better airflow (turbocharger with ported heads, or a cam and ported heads, for example).
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Aug 9, 2011 | 12:42 AM
  #14  
Re: V6 hard to take off when hot
problem solved. It was chinese pressure plate. Now i have Valeo clutch kit installed . This one http://cgi.ebay.com/ebaymotors/ws/eB...%3D1&viewitem=

Car works fine
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Aug 9, 2011 | 07:01 PM
  #15  
Re: V6 hard to take off when hot
Quote: problem solved. It was chinese pressure plate. Now i have Valeo clutch kit installed . This one http://cgi.ebay.com/ebaymotors/ws/eB...%3D1&viewitem=

Car works fine
I'd like to thank you for getting back to us on the issue. This always helps others. As for the clutch assembly, pressure plate, been-there-done-that (BTDT). It can be tough to get a proper set up that doesn't chatter.

The current one in the Firebird chatters a little when cold. But then as it heats up it becomes smooth and drive-able. This I can live with.

Not the opposite though. Smooth when cold and chatter when hot, forget it.

RBob.
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Aug 31, 2011 | 03:53 AM
  #16  
Re: V6 hard to take off when hot
dont buy AcDelco clutch kits, some of them are chinese
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