Jump to content
HybridZ

Help! Starts and Runs Then...


dwarlick

Recommended Posts

This is my first video since I got My R33 RB26DETT running in my '71 Series 1. I have several issues but first and foremost it runs like crap after it warms up. I have searched and found a few posts on this problem but I was hoping these videos might provide a more specific diagnosis. If you full screen the video you can see the throttle movement if that helps.

Cold Start

 

Then after running for about 3 min:

 

Warmed UP

 

Thank you all in advance. I really don't know where I'd be without HybridZ. I know I would never have attempted something like this without your inspiration.

Link to comment
Share on other sites

Its kinda hard to tell what is going on from the video but here it goes...

 

Is that it just idling after warmup or are you having to blip the throttle to keep it running?

 

Are you getting spark and fuel to all cyls? You may want to check your timing as well as your throttle linkage to make sure the idle contact switch is being hit when the throttle plate is closed. Are your o2 sensors hooked up and good?

Link to comment
Share on other sites

This brings me to my next point the O2 sensors are not hooked up.:shock:

My harness was a little hacked up and I don't have the harness side of the connectors. I don't know where exactly the wires are on the harness any pics would help. I realize that this is an import detail to leave out but it slipped my mind and I'm kind of a Jack Ass. As I stated before I would not have ever attempted a swap like this without this board's help, and to this point you have given me enough information to be dangerous. But seriously, I hope I don't burn down my garage.:flamedevi

Link to comment
Share on other sites

You dont need O2 sensors to run right. The car will run "okay" without them. They are for fine tuning the fuel mixture and swinging the fuel mixture for a cat. If you dont have them the ecu will just not go into closed loop. It wont run great but you may not be able to even tell the difference in most cases. Usually the first sign is poor gas mileage followed by the MIL.

 

Its very hard to diagnose what is going on in the videos there. Can you report back with what it smells like? take a look at your exhaust and see if it is black or tan or smells funny. Maybe it burns your eyes when you look under there? You need some diagnosis tools. fuel pressure guage for one. A can of brake cleaner as well to check for vacuum leaks. You should also double check your wiring. If the O2 sensors harness was cut, what else was disrupted? There are numerous things that could cause your engine to act up. The ECU on these engines is smart enough to "mask" other problems and make it a total pain to diagnose the real issue.

Link to comment
Share on other sites

Thanks for the effort Mike.

 

Rayaapp - I was thinking the O2 sensor may not cause this much of a problem. As far as fuel pressure I will pick up a gauge asap. But, I have a brand new walbro 255 and like I said the when I loosened the clamp to the fuel rail and the fuel pressure seemed really strong. Also, it smells rich for sure.

 

noodl35- when its cold I can rev up really high and let off and it will go back to idle. After it warms up almost no throttle and if I do rev it, it putters and coughs and wants to die unless I feather the throttle and sometimes to no avail and it dies anyway.

Link to comment
Share on other sites

Thanks for the effort Mike.

 

Rayaapp - I was thinking the O2 sensor may not cause this much of a problem. As far as fuel pressure I will pick up a gauge asap. But, I have a brand new walbro 255 and like I said the when I loosened the clamp to the fuel rail and the fuel pressure seemed really strong. Also, it smells rich for sure.

 

noodl35- when its cold I can rev up really high and let off and it will go back to idle. After it warms up almost no throttle and if I do rev it, it putters and coughs and wants to die unless I feather the throttle and sometimes to no avail and it dies anyway.

 

 

Just because you have a good pump or new pump doesnt mean there isnt a problem. Old cars with small or clogged return lines will spike pressure. If you dead head the return line the pressure will spike up past 110psi easily. A pressure gauge will make sure you are within spec. My guess was that you were running rich. If all checks out start looking for vacuum leaks.

Link to comment
Share on other sites

first thing is to find out is it ignition or fuel problem. Most likely fuel problem by hearing the engine sound. Now is it too rich or too lean, most likely too lean if it's ok when cold. To find out just pinch the fuel return line with plier to increase the fuel pressure while engine is running, if it gets better it's too lean ,worse too rich. So now you can narrow down the problem. On Rb26 fuel is added or measured by maf,tps,coolant tempsensor,intake air temp sensor. Maf do most. make sure you don't have the rom tuned ecu that has Z32 maf calibration. if you have friend with Rb26 Power Fc You can use commender to see which sensors are bad.

Link to comment
Share on other sites

If it revs and runs fine cold yet after it warms up it runs poorly its probably because its kicking into closed loop and without the o2 sensors it cannot properly meter the fuel/ignition etc... normally most ECU's wont click to closed unless they have varying o2 voltage but who knows with the RB ecu... we are talling about pre OBDII days here... If you have a consult/blaZt or something you could easily see whats going on. Its pretty handy if you are going to be running a stock ECU for awhile. I have my old blaZt in my closet if you are interested in buying it, I used it for about a week to diagnose startup issues on my swap and then went with an AEM EMS.

Link to comment
Share on other sites

Exactly what I am thinking.

 

I see this symptom about 4 times a day during my 20 call average day.

 

The ecu isn't liking a signal that it requires when going into closed loop operation.

 

I'm not sure what they have in japan but one would think they don't dumb down the ecus since they already make them damn smart for the US market.

 

They should have some sort of freeze frame data that records the datalist at the time the ecu detects a problem.

Link to comment
Share on other sites

  • 2 weeks later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...