Restricted revs - intermittent

User avatar
Terry
E30 Guy
Posts: 43
Joined: Tue Aug 21, 2012 1:37 am
AntiSpam: No
Location: St. Louis

Restricted revs - intermittent

Postby Terry » Thu Aug 07, 2014 12:19 am

The shop putting my s50 swap together is still trying to sort some things out...
Revs are intermittently restricted to 3500, which happened for about 1/2 hour, and then it went back to driving normally.
They might or might not figure it out, but still wanted some ideas in case I need to suggest...
User avatar
Yoshi
Site Admin
Posts: 9093
Joined: Thu Feb 26, 2009 7:47 pm
AntiSpam: No
Location: North VA
Contact:

Re: Restricted revs - intermittent

Postby Yoshi » Thu Aug 07, 2014 11:03 am

Could be dead/dying coils or misgapped spark plugs. You mean the rpm gauge is stuck or the car won't rev past that point?
Image
Status: HG repair. 488wtq though!
User avatar
Terry
E30 Guy
Posts: 43
Joined: Tue Aug 21, 2012 1:37 am
AntiSpam: No
Location: St. Louis

Re: Restricted revs - intermittent

Postby Terry » Thu Aug 07, 2014 5:32 pm

The actual engine woudn't go past 3500 when reved for a while on the highway, and then all of the sudden went back to normal.
User avatar
M20_fever
Größter Vorsitzender
Posts: 11029
Joined: Fri Feb 27, 2009 1:28 pm
AntiSpam: No
Location: Northern IL

Re: Restricted revs - intermittent

Postby M20_fever » Tue Aug 12, 2014 5:02 pm

Failing CPS maybe, Bentley should have test values.
Image
Midwestern Councel C Prepared class champion 2012
North Suburban Sports Car Club C Prepared class champion 2012
HSAX Instructor

GET YOUR E3P GEAR HERE: http://www.cafepress.com/e3pgearshop
User avatar
Terry
E30 Guy
Posts: 43
Joined: Tue Aug 21, 2012 1:37 am
AntiSpam: No
Location: St. Louis

Re: Restricted revs - intermittent

Postby Terry » Sat Aug 16, 2014 7:56 pm

Shop says CP sensor is ok, now he says maybe the fuel pump may not be sufficient. I know this shouldn't be true. I didn't find any direct info on the stock e30 '88+ pump used with S50us, but I think this quote I found gives a good idea of what the pump is capable of...

"I can't seem to find any specs on VDO pumps. But, the 87 e30 M3 used a Bosch pump, rated at 130 l/h (part # 0 580 464 070). And the VDO pump with #228 220 007 001Z was used in all of the later e30's including the 2.3L EVO II.

The M60 engine is rated at 282HP +/-. Given a BSFC of .5 for a typical naturally aspirated engine, the engine will consume about 141 lbs/hr of fuel, which converts to about 89 l/h. This is well below the 130 l/h rating for the 87 M3. All of the systems are operating at 3 bar, so no need to recalculate flow ratings based on differing pressures.

If you make the engine less efficient (BSFC = .6), and bump up the horsepower (315HP), the result is 119 l/h, which is within 10% of the 87 M3 Bosch pump. However, if the early e30's had a two pump system (in-tank low pressure + external HP), then the effective flow-rate would be higher. This aggregate capacity would be necessarily matched by the VDO pump, so the effective headroom would be higher."


I looked at a post here: http://www.e30performance.info/viewtopi ... =35&t=1812
and this might be something, so I will have the mechanic look in the tank for rust.
User avatar
Yoshi
Site Admin
Posts: 9093
Joined: Thu Feb 26, 2009 7:47 pm
AntiSpam: No
Location: North VA
Contact:

Re: Restricted revs - intermittent

Postby Yoshi » Mon Aug 18, 2014 11:42 am

A fuel pressure gauge will help you diagnose SO much of that pretty quickly.
Image
Status: HG repair. 488wtq though!
User avatar
Terry
E30 Guy
Posts: 43
Joined: Tue Aug 21, 2012 1:37 am
AntiSpam: No
Location: St. Louis

Re: Restricted revs - intermittent

Postby Terry » Mon Aug 18, 2014 6:31 pm

yeah, they just put one on...
User avatar
Yoshi
Site Admin
Posts: 9093
Joined: Thu Feb 26, 2009 7:47 pm
AntiSpam: No
Location: North VA
Contact:

Re: Restricted revs - intermittent

Postby Yoshi » Tue Aug 19, 2014 11:10 am

Keep us updated!
Image
Status: HG repair. 488wtq though!
User avatar
Terry
E30 Guy
Posts: 43
Joined: Tue Aug 21, 2012 1:37 am
AntiSpam: No
Location: St. Louis

Re: Restricted revs - intermittent

Postby Terry » Tue Aug 19, 2014 3:30 pm

The ongoing saga of my diy, then outsourced swap...
Bill is now approaching 9 grand, albeit, I'm pretty much addressing everything, but this issue seems to have got the shop guys a little stumped.
User avatar
Yoshi
Site Admin
Posts: 9093
Joined: Thu Feb 26, 2009 7:47 pm
AntiSpam: No
Location: North VA
Contact:

Re: Restricted revs - intermittent

Postby Yoshi » Tue Aug 19, 2014 4:41 pm

Really shouldn't be that big of an issue. Only so many things could be the issue.
Image
Status: HG repair. 488wtq though!
User avatar
Ryki
I <3 E30's
Posts: 1009
Joined: Wed Dec 19, 2012 11:15 am
AntiSpam: No
Location: Germany

Re: Restricted revs - intermittent

Postby Ryki » Sat Aug 23, 2014 7:20 pm

Question, how did they test the CPS?
User avatar
M20_fever
Größter Vorsitzender
Posts: 11029
Joined: Fri Feb 27, 2009 1:28 pm
AntiSpam: No
Location: Northern IL

Re: Restricted revs - intermittent

Postby M20_fever » Sun Aug 24, 2014 10:00 am

$9000 USD??? Good god, and they still can't find a hesitation? Is it doing this only at WOT or even if the throttle is eased up to redline? I mean, its got to either be cps, tps, maf, or a failing ignition components. How could it cost $9 grand to diagnosis that?
Image
Midwestern Councel C Prepared class champion 2012
North Suburban Sports Car Club C Prepared class champion 2012
HSAX Instructor

GET YOUR E3P GEAR HERE: http://www.cafepress.com/e3pgearshop
User avatar
Terry
E30 Guy
Posts: 43
Joined: Tue Aug 21, 2012 1:37 am
AntiSpam: No
Location: St. Louis

Re: Restricted revs - intermittent

Postby Terry » Mon Aug 25, 2014 2:03 am

They have one really sharp mechanic, so if he's not freed up, I have to just wait. The car was with them for a year, and I just got it back on Friday. 9 grand included a lot of stuff (minus hesitation :(). They told me to just watch fuel pressure, etc, and bring it back to them with my observations. They changed fuel filter to see if that did it. Might have done it, because in my total 25 mile drive I couldn't reproduce it: not going above 3500 rpm. Only once, about 5500 rpms, it felt bogged down, but then I think I depressed the clutch and let it out again and it was ok.
I asked about if they tested the CPS, and I don't think they did actually test it.
Looks like I'll do it myself.

I had a build site going here originally, a while back, but when my wife got pregnant again, things got/are hectic around here. I'll take some of my questions over there, because I have a lot concerning wheel/tire size options to better suit my high diff, chip options, etc.

Even if it's not perfect yet, and the price is a little more than I expected, I'm still pretty happy.
User avatar
Yoshi
Site Admin
Posts: 9093
Joined: Thu Feb 26, 2009 7:47 pm
AntiSpam: No
Location: North VA
Contact:

Re: Restricted revs - intermittent

Postby Yoshi » Mon Aug 25, 2014 11:17 am

Car better be damn near perfect for $9k. lol "wife got pregnant again". Sounds like she caught a cold.
Image
Status: HG repair. 488wtq though!
User avatar
Terry
E30 Guy
Posts: 43
Joined: Tue Aug 21, 2012 1:37 am
AntiSpam: No
Location: St. Louis

Re: Restricted revs - intermittent

Postby Terry » Tue Aug 26, 2014 1:59 am

Yes, it does sound a little insensitive... but even when people do try to sound sensitive when announcing a birth, they say "we"... on the second + child you know that's total b.s.

Now the car occasionally surges between 500 and 1,000 at idle, whether the engine is warmed up or not. I rev it a couple of times, and it seems to go away.

I'll drive it for a couple more days, because obviously there are some issues to be addressed.

Return to “General Tech”

Who is online

Users browsing this forum: No registered users and 1 guest