Cold start issue still continues...

[PsorianoPre99A4]

Still trying to figure out my cold start issue.. Does anyone have any ideas? My set up is in my Signature.

Symptoms:
- It will take a long crank or rough start before startup in the AM after a night of sitting. Sometimes it will take two cranks.
- After going into a store or the gym and than back out, it will start up easier or normal.
- My vacuum (-16) and idle (1.4k) is normally high on cold start ups than goes down when more warm, 19 Vacuum, 800k rpm. (I think its normal for tuned cars to start high on cold start?)
- Also randomly in idle (not normally) the vacuum will go up as well as the idle, but i just tap the pedal and it'll go back to normal.
- I boost to about 18-20psi, tune calls for 22psi~. (I have a MBC I'm running that I set to that)
- I also have an exhaust leak between my EM and my turbo. I have to change that gasket out still, somehow it blew out? (no idea) But it does make a rattle noise up front on cold start, not sure if that is affecting my cold start issue as well. I plan on fixing it in the next week or so.

What i've changed so far:
- Walbro Fuel Pump 255lph
- New Fuel Filter
- New MAF housing & Sensor
- New 630CC Ringer racing injectors
- ECS 2.0 coil conversion, ICM Delete
- New Interstate battery
- OEM CTS


I feel like I changed everything already but it still continues. Is there anywhere I should look? Or is this a normal thing with tuned cars having rough cold starts? Other than that, my car drives great.

[Karlo]

Dirty throttle body?

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[kjames1270]

I'm having similar issues. The check valve idea right after the fuel pump was done by Seerlah, a member here. Gonna give it a try

http://www.bmwe34.net/E34main/Trouble/535ihot_start.htm

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[seanf86]

Being aeb it could be the beginnings of the failure of your throttle body, mine I tried adapting and it failed saying could not adapt. Ended up getting a used replacement and adapting it.

[PsorianoPre99A4]

Being aeb it could be the beginnings of the failure of your throttle body, mine I tried adapting and it failed saying could not adapt. Ended up getting a used replacement and adapting it.

I forgot to mention that I just got a different throttle body from another car and manually adapted it, because I was having "fault in basic settings" issues of adapting before. Not throwing any codes now after erasing the codes in vagcom.

[PsorianoPre99A4]

I'm having similar issues. The check valve idea right after the fuel pump was done by Seerlah, a member here. Gonna give it a try

http://www.bmwe34.net/E34main/Trouble/535ihot_start.htm

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We have a check valve in the fuel pump lines?

[seanf86]

We have a check valve in the fuel pump lines?

It's in the pump I believe

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[PsorianoPre99A4]

It's in the pump I believe

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I just replaced the entire pump and and basket with a walbro.

[seanf86]

I just replaced the entire pump and and basket with a walbro.

It may not have a built in check valve that I don't know.

Another thought since you've done CTS and a throttle body is the crank sensor, usually they fail when hot but ohm it out when cold, the fuel pump doesn't start pumping until it sees cranking, if the sensor is failing it could be the problem. I don't know the specs of it but it's in a Bentley manual and possibly online.

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[PsorianoPre99A4]

It may not have a built in check valve that I don't know.

Another thought since you've done CTS and a throttle body is the crank sensor, usually they fail when hot but ohm it out when cold, the fuel pump doesn't start pumping until it sees cranking, if the sensor is failing it could be the problem. I don't know the specs of it but it's in a Bentley manual and possibly online.

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The PO changed the CPS about 40k ago & there isn't a code for it. This is just a sign of it slowly dying? How often do they go?

[Avant Nate]

In my case, aftermarket tunes did not prime my pump. Put a stock computer in, primes, aftermarket, no prime. This is for Unitronic and Maestro, dont remember if it did on older tunes as well. Can you hear the pump prime?

[PsorianoPre99A4]

In my case, aftermarket tunes did not prime my pump. Put a stock computer in, primes, aftermarket, no prime. This is for Unitronic and Maestro, dont remember if it did on older tunes as well. Can you hear the pump prime?

Yup I definitely hear the pump prime.

- - - Updated - - -

In my case, aftermarket tunes did not prime my pump. Put a stock computer in, primes, aftermarket, no prime. This is for Unitronic and Maestro, dont remember if it did on older tunes as well. Can you hear the pump prime?

I've also heard thats the case for aftermarket tunes. But i'm not sure.

[Nollywood]

I would be looking at fuel rail hold pressure. Unlike the B6 1.8T, the AEB in the B5 has a return. Check the fuel pressure regulator. Pull off the vacuum line, and try sucking from the diaphragm end. A torn diaphragm will meet with little or no resistance. If there's any gas residue in the vacuum line, or any gas dribbles out, it's shot, and should be replaced.

The internal spring could also be bad, this will allow the pressure in the rail to drop, and the fuel to drain back to the tank after shut down. The fuel pump only primes so much upon starting, it will not give max pressure to an empty rail.

Try this after the car has been stood overnight:

Turn the ignition on, then off, a few times, making sure the fuel pump primes each time. It should get to the point you wouldn't hear the pump much, as the rail pressurises. Then try starting the engine. Does it start easier?

You can also run the fuel pump constantly, before starting. This can be achieved by pulling the fuel pump relay, and applying a jumper cable to terminal 30 and 87a. Or open the relay, then manually close the contacts to activate the pump. Then try starting. If it starts as normal, then you've got a fuel pressure issue, which would point to a tired FPR.

[PsorianoPre99A4]

I would be looking at fuel rail hold pressure. Unlike the B6 1.8T, the AEB in the B5 has a return. Check the fuel pressure regulator. Pull off the vacuum line, and try sucking from the diaphragm end. A torn diaphragm will meet with little or no resistance. If there's any gas residue in the vacuum line, or any gas dribbles out, it's shot, and should be replaced.

The internal spring could also be bad, this will allow the pressure in the rail to drop, and the fuel to drain back to the tank after shut down. The fuel pump only primes so much upon starting, it will not give max pressure to an empty rail.

Try this after the car has been stood overnight:

Turn the ignition on, then off, a few times, making sure the fuel pump primes each time. It should get to the point you wouldn't hear the pump much, as the rail pressurises. Then try starting the engine. Does it start easier?

You can also run the fuel pump constantly, before starting. This can be achieved by pulling the fuel pump relay, and applying a jumper cable to terminal 30 and 87a. Or open the relay, then manually close the contacts to activate the pump. Then try starting. If it starts as normal, then you've got a fuel pressure issue, which would point to a tired FPR.

Thanks for the reply Nollywood. I pulled off the vacuum line and didn't notice anything drip. When you say "pull off the vacuum line, and suck from the diaphragm end" what do you mean by that?. I haven't yet bought a FPR because I want to make sure thats the issue, i've spent a bunch of money trying to chase this cold start issue. It always starts up right away on the second start. Any other ideas anyone??? I still have no codes.

[WyGuy1.8T]

Just a thought, maybe you don't have enough cranking fueling in your tune? Did you have the problem prior to having it tuned?

[PsorianoPre99A4]

It wasn't as bad I suppose, but than again this could be an overtime kind of thing. Just wanting to know where else to look? Wondering if I should re Gap plugs. Since I got bigger coils


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[Turbo_B5]

My 97 had a problem like this and it ended up being low compression.

[PsorianoPre99A4]

What would cause low compression?


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[WyGuy1.8T]

What would cause low compression?


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Over time your piston rings wear down from friction on the cylinder walls, so you don't have a good seal in the cylinder. Your valve seats can also not seal on the cylinder head as well as they did from the factory, which has the same effect.

And as far as the bigger coils go, if your plugs are gapped at .028, you're fine. There is some controversy on whether or not running a larger gaps on plugs with the 2.0 coils gives you more power, some people had different dyno results, different theories, etc.

[PsorianoPre99A4]

What signs of drivability would lead to low compression?
My car drives hard and boost right away. No codes. Is there any other signs that would point to low compression? The car is old, but there is only 138mi on the motor, and it's been treated well it's life.


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[Turbo_B5]

Well do a compression test and find out the health of the engine. My car lost compression on cyl one and it took longer and longer to start up untill it just wouldn't anymore. Piston rings where bad.

[PsorianoPre99A4]

Ok is it pretty simple to do with these cars? Is there any other areas I could check instead of compression, I feel like it can't be if my idle is generally good and no issues really other than a slower cold start. It also isn't consistent.


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[Turbo_B5]

Ok is it pretty simple to do with these cars? Is there any other areas I could check instead of compression, I feel like it can't be if my idle is generally good and no issues really other than a slower cold start. It also isn't consistent.


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Yep Just do the compression test. Nothing else easier to check. From what you are describing and my past experience it is worn piston rings. 100PSI is the rebuild limit and 43PSI difference between cylinders is also NFG.

[PsorianoPre99A4]

Yep Just do the compression test. Nothing else easier to check. From what you are describing and my past experience it is worn piston rings. 100PSI is the rebuild limit and 43PSI difference between cylinders is also NFG.

Whats NFG? I don't have the tool to do the compression test. I'll have to ask around or just take it in. However, I was thinking I could also try the fuel pump relay or the CPS. I just changed the fuel regulator and set my DV splitter to recirculation.

[Turbo_B5]

no fucking good.... hurry up and do a compression test... like your in the states. go to horrible freight and get one. http://www.harborfreight.com/compres...-pc-62638.html

[PsorianoPre99A4]

Ok what should the psi range be for each cylinder? And if I have low compression on one of the cylinders am I screwed? How long did this persist for you when it happened to you?


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[Turbo_B5]

Ok what should the psi range be for each cylinder? And if I have low compression on one of the cylinders am I screwed? How long did this persist for you when it happened to you?


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rebuild limit is 100psi and the maximum psi difference between cylinders is 43psi. so above 100 and within 43 of eachother. the car fires on cylinder one so that is the one that sounds like its low compression. I had the issue for probably the whole ownership. 265kms-311kms which it died at with 50~psi on cyl 1.

[PsorianoPre99A4]

rebuild limit is 100psi and the maximum psi difference between cylinders is 43psi. so above 100 and within 43 of eachother. the car fires on cylinder one so that is the one that sounds like its low compression. I had the issue for probably the whole ownership. 265kms-311kms which it died at with 50~psi on cyl 1.

Ok Cylinder one is the closet to the T belt right? My car is only at 138k (222 kms). It is still inconsistent. I will update once i do a compression check. Thanks King.

[woolveren]

Could be a failing crank shaft sensor, you can check the resistance between its pins to confirm it falls in the spec.

[PsorianoPre99A4]

Could be a failing crank shaft sensor, you can check the resistance between its pins to confirm it falls in the spec.

My cousin was saying this too. It has been changed already once in the car about 50k ago. How do I check the resistance between its pins? Do I have to take it off first?

[PsorianoPre99A4]

Update Post:
Changed the Crank Position Sensor and Fuel Pressure Regulator still having the cold long start issue approximately 4-6 seconds now. Three seconds when sitting for a few hours. In consistent honestly. Sometimes it starts after 1-2 seconds (normal?) Idk what the issue is. My car boosts to 22psi and drives great. Vacuum generally stays around 18-20hg, idle always at 800. I took it to a known tech locally and he said to recheck the fuel line that connects to the pump when I replaced it, mentioning the screw clamps don't hold a good seal on the accordion looking hose that normally goes with the OEM pump. He said I should switch to actual fuel rubber hose when I did the fuel pump, will do that next and recheck work. Everything else checks out, air/fuel/spark wise. Also haven't replaced the fuel pump relay, but I don't have codes so I didn't try. Any other suggestions from here would be helpful...stumped.

[Turbo_B5]

did you compression test like i said months ago? Doesn't sound like it. I literally changed everything on my aeb and the problem was low compression so fucking test it.

[Spectre1130]

did you compression test like i said months ago? Doesn't sound like it. I literally changed everything on my aeb and the problem was low compression so fucking test it.

Do this. I had an issue like that and it was a leaking headgasket as well as dirty valve seats (rebuilt my bottom end 15k miles before so I knew rings weren't bad). Compression test takes maybe 10 minutes. Just pull all your spark plugs out and put the tester in cylinder 1, crank for 8-10 seconds or until the pressure stops rising. Repeat in cylinders 2/3/4. Log the pressures and compare them.

[PsorianoPre99A4]

I highly doubt it's compression, had an experienced mechanic who owns multiple b5s say the same. Didn't do the test but I will, I have. I doubt in my mind compression will be fine.


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[PsorianoPre99A4]

Don't I do it one at a time? Not take all the plugs out? I have to source a gauge too.


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[Turbo_B5]

you take it out them all out so the crank spins freely. do the fucking test or stop asking for help.

[Spectre1130]

Don't I do it one at a time? Not take all the plugs out? I have to source a gauge too.


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If you leave the others in and you have a leak between cylinders it wont be as noticeable. After doing the test with them all out, then if you so desire you can check for leakage between cylinders, but no point because you have to replace it anyways if its bad. So take all 4 out, then check compression on them one at a time.

Harbor freight sells them for dirt cheap. Part stores will probably rent them out for free. Also, no offense to your friend but "experienced mechanics" are a dime a dozen on forums. I've seen a million times where people say a certified/professional mechanic did this or that and its wrong.

[PsorianoPre99A4]

UPDATE:

Did compression test, drove around, came back home after car was at operating temperature, ten minutes later, did test.
Starting with the cylinder in the front of the car to the back of the motor 154, 154, 146, 130

So would that be the cause of my cold start issue? I haven't replaced the fuel line in the pump yet, but any other ideas?

[PsorianoPre99A4]

Bump..I'm thinking it's fuel related. Carbon build up? Any other suggestions to move forward? Are these numbers bad?


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[425A4]

Read a book... specifically a workshop manual. All the info your need is in there, wrote by the engineers that built your car. Or pay a professional to diagnose it.