M60 slowwwww throttle response

[Deadwake]

Hi guys! So my friend just bought a 97 740i with the m62 non tu engine, I'll post in the e38 forums as well, but just wanted to post here cause I know there are some m60/m62 gurus on this forum.

So we got it super cheap, 500 bucks, it had a dead battery but started right up when we jumped it. Motor sounds great, honestly probably the best sounding m62 I've heard with over 120k miles.

However, it came with some fun stuff to fix before it can be fully enjoyed:

Engine codes as read by a OBD2 reader (all I have unfortunately) are P0173 and P0170, fuel trim malfunction on both banks, most likely related, the throttle is suppppppppper slow to respond, like it gets up to speed and it has power but the power isnt the great and is delivered 2-3 seconds after applying pressure to the gas, however the throttle cables look right, I see them open the throttle body when my friend gives it gas, but the power kicks in late.

There are new hose clamps all over the vacuum system, someone was trying to hunt this down before it would seem, I hear a loud vacuum sound from the back of the engine, so in the meantime I'm gonna replace the CCV with a spare I have lying around and get a fuel pressure tester to see if the fuel pressure is right but any advice or suggestions would be great.

Also, I noticed it has a second cable connecting to a throttle plate closer to the maf, super weird but that cable is crazy loose and the plate is always open, when my friend presses the gas, that cable doesnt move at all.

Thanks!

[JimLev]

In addition to what you mentioned above look inside the throttle body to see if it's full of carbon and oil.
That second cable is probably for the ASC.

[Deadwake]

ASC! That makes sense. I'll take a closer look for gunk when we work on it tomorrow. Thanks!

[edjack]

The ASC cable s/b as taught as the throttle cable. Perhaps the motor is defective. However, that is not your problem.

How much vacuum are you pulling at idle? S/b 18-20 in, and steady.

[Deadwake]

The ASC cable s/b as taught as the throttle cable. Perhaps the motor is defective. However, that is not your problem.

How much vacuum are you pulling at idle? S/b 18-20 in, and steady.

Excuse the ignorance, but where can I hook up a vacuum tester? I know where to test fuel pressure but don't see anywhere obvious on the intake.

[JimLev]

Under the engine top cover you'll see 2 small rubber hoses that attach to the back of the intake manifold. Either one will have vacuum on it.

[Deadwake]

Under the engine top cover you'll see 2 small rubber hoses that attach to the back of the intake manifold. Either one will have vacuum on it.

Really appreciate it, I'll let you guys know what I find.

[Deadwake]

I took a video of the vacuum leak for your guys consideration: https://youtu.be/I-g3sninoLY

looks like a hose is missing/cut on the driver side(US) of the CCV, on my e39 that connects to the firewall or maybe something near the brake booster. I think this is probably the issue, do you guys have any idea where the line is supposed to go?

[JimLev]

You should have a hose connected to the top drivers side of the rear cover (CCV) that connects to evaporative emission stuff that is behind the rear drivers side fender liner.

[Deadwake]

You should have a hose connected to the top drivers side of the rear cover (CCV) that connects to evaporative emission stuff that is behind the rear drivers side fender liner.

Did some investigation last night on car and found that hose isn't there and the port on the CCV is capped, which looks factory. It snowed pretty good and we couldn't get it to a garage to work on, but we're going to take the intake manifold off and replace all the gaskets as well as tackle the VCGs at the same time in the near future.

We did tighten the throttle cable and that eliminated the throttle lag but it still feels down on power compared to my m62tu . You can clearly hear what sounds like I massive air leak coming from the rear of the intake manifold but what's weird is how smooth the idle is, besides the low power the engine sounds great.

[Deadwake]

Update on this, the car got much worse and became nearly undrivable. The symptoms seemed very similar to my car when my MAF failed, went and pulled one out of a salvage yard, slapped it in and it's driving like a new car! Cleared the codes and drove it around a bit and it's really good. Not bad for 500 bucks!