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93' K5 Blazer 5.7 TBI Cold start flooding issue
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SuncrestSniper
User
Sep 23, 2012, 12:00 PM
Post #1 of 66
(8821 views)
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93' K5 Blazer 5.7 TBI Cold start flooding issue
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Hey gang new here and in need of some help.
I have a 93' Chevy K5 Blazer that developed a cold start issue just recently since the temps have started hitting the 40's at night here in Eastern Washington state. Mileage on the engine is less than 5000.
It's flooding out in the mornings right off the bat. Once you do get it running it runs fine all day long.
I have replaced the following so far.
1) Delco CTS sensor
2) TPS
3) IAC
4) MAP
5) Delco Spark Plugs
6) ECM
7) New Interstate Battery
8) Delco 100 amp Alternator
9) Air Filter
10) CTS pig tail
11) Cleaned engine to body to chassis ground and CTS ground to engine
12) new injectors
What we have checked.
1) No vacuum leaks
2) Great fuel pressure (gauge installed at TBI reading @ 12 to 13 PSI)
3) Timing is spot on (Advanced correctly for the bigger cam)
4) No leaking injectors (both new)
5) Fuel regulator not leaking down (holds pressure all night long no signs of leaks)
6) good oil pressure while cranking (GM dash gauge)
Engine is a Built SB
204/214 cam
roller tip rockers
TBI spacer
Full MSD ignition (distributor etc. etc.)
Hooker headers
Flowmaster mufflers
SuperTrapp Baffled tips
TBIChips.com custom chip
Computer kicks no codes
Ran with no issues last winter
We let it sit in my mechanic's shop one night and it started the next morning just fine.
I took it back home and the next morning it was 40 again and it flooded again.
Has anyone run into anything this strange before?
What else should I check?
Thanks in advance for any tips or help,
SS
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SuncrestSniper
User
Sep 23, 2012, 2:14 PM
Post #2 of 66
(8796 views)
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Re: 93' K5 Blazer 5.7 TBI Cold start flooding issue
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On a side note I pulled the MSD cap and rotor out today to find out that the cap looked like hell. After cleaning the little mountains of carbon off the contact points with a dremel and light wire wheel the inspection revealed some nasty rough worn channels in them. I will get a new cap and rotor this week but I don't think this going to solve my main issue.
SS
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nickwarner
Veteran
/ Moderator
Sep 23, 2012, 6:33 PM
Post #3 of 66
(8779 views)
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Re: 93' K5 Blazer 5.7 TBI Cold start flooding issue
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That cap and rotor could very well be your only issue. Weak spark on a cold morning means no start or poor start, with flooding to be expected. Don't overlook the small things.
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SuncrestSniper
User
Sep 23, 2012, 7:48 PM
Post #4 of 66
(8769 views)
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Re: 93' K5 Blazer 5.7 TBI Cold start flooding issue
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Well after cleaning the cap and rotor it misses like crazy now under load. I'll grab new ones in the morning and report back after work.
SS
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SuncrestSniper
User
Sep 24, 2012, 9:35 AM
Post #5 of 66
(8759 views)
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Re: 93' K5 Blazer 5.7 TBI Cold start flooding issue
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I forgot I had the original Distributor in my garage. The cap and rotor off it were nice and clean so i tossed them on first thing this morning before I tried to start it. Same thing again flooded. What's next?
SS
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nickwarner
Veteran
/ Moderator
Sep 24, 2012, 6:06 PM
Post #6 of 66
(8749 views)
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Re: 93' K5 Blazer 5.7 TBI Cold start flooding issue
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Looked a bit closer at the first post under what you've checked. You listed no injector leakdown because the injectors are new. New doesn't mean good, just means new. Did they get replaced before or after this issue started?
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SuncrestSniper
User
Sep 24, 2012, 6:12 PM
Post #7 of 66
(8746 views)
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Re: 93' K5 Blazer 5.7 TBI Cold start flooding issue
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Replaced last week. Dry as a bone in the mornings. No leaking from them or the regulator.
SS
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Discretesignals
Ultimate Carjunky
/ Moderator
Sep 24, 2012, 6:53 PM
Post #8 of 66
(8741 views)
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Re: 93' K5 Blazer 5.7 TBI Cold start flooding issue
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What is the MAP sensor voltage with the key on? Take a vacuum pump and connect it to the vacuum hose going to the MAP sensor. Increase the vacuum. Does the MAP sensor voltage lower? What is the MAP sensor voltage at 18-22 inches of vacuum?
What is your ECT voltage with the key on engine cold (take note of the ambient temperature).
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Sep 24, 2012, 6:54 PM)
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SuncrestSniper
User
Sep 25, 2012, 12:58 PM
Post #9 of 66
(8728 views)
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Re: 93' K5 Blazer 5.7 TBI Cold start flooding issue
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I''l have to test it. It is only a week old and we did try three others with no changes. It runs fine once warm and I was under the assumption that the MAP had nothing to do with start up?
SS
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Discretesignals
Ultimate Carjunky
/ Moderator
Sep 25, 2012, 5:02 PM
Post #10 of 66
(8720 views)
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Re: 93' K5 Blazer 5.7 TBI Cold start flooding issue
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The MAP sensor really doesn't play too much of a role during starting, but was just wondering what the MAP sensor was putting out and if it is operating correctly. The ECM may be getting the BARO reading off the MAP sensor signal to adjust from changes in atmospheric air pressure. Not only does that tell you if the MAP is good, but it tells you if it is receiving power and has a ground. Of course, you don't know if the signal is reaching the ECM or not. Seeing you had changed the cam profile, wondering how much it has affected manifold pressure. The higher the manifold pressure at idle the more fuel the ECM is going to add to the base injector pulse. I am sure your tuning chip has compensated for this somehow.
Does the engine run rich when it is warmed up? Really need some more data such as block learn and integrator values, injector pulse width, ECT, timing advance, etc. from a scan tool to get an idea what is going on with it.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Sep 25, 2012, 5:04 PM)
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SuncrestSniper
User
Sep 25, 2012, 5:17 PM
Post #11 of 66
(8715 views)
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Re: 93' K5 Blazer 5.7 TBI Cold start flooding issue
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It does run rich due to lack the back pressure which is why I added the Super Trapp Disc tips 2 months ago. The truck has run for the last year and a half with no issues other than poor take off power and bad gas mileage. Since the install of the Trapp tips my mileage has shot way up and there is no lag at take off. Still a bit rich but a whole lot better than it was. This whole issue of the cold starts started when I drove it to Bonneville a couple weeks ago. After driving from Spokane,WA to bonneville the next morning down there was when it first did it. Once warm she'd run all day long pulling our slat flat car and only burning maybe 10 gallons of fuel every hour and a half. It's something temp related because if it doesn't get up to operating temp before I try to drive it it will spit and sputter. Once it's up to @ 195 to 200 degrees it's fine.
The exhaust tips are the only change that I have done to it other than the list of new parts above that were installed last week.
I'm putting a new fuel pressure gauge on behind the TBI tonight to make sure the one on there now isn't faulty.
SS
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nickwarner
Veteran
/ Moderator
Sep 25, 2012, 5:27 PM
Post #12 of 66
(8710 views)
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Re: 93' K5 Blazer 5.7 TBI Cold start flooding issue
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Why did you go with the carb spec cam instead of the TBI spec one? Your intake lift and duration may be contributing to the issue even though its held up for a short bit before. I'm looking at the Edelbrock Performer cam specs right now. For the regular carbed engines the duration at .050 are 204/214 like what you have, with .420/.442 lift. But the Performer cam for TBI is 194/214 @.050 and .398/442 lift. They didn't change the intake lift and duration on the TBI cam for nothing. Also, are these rockers stock ratio or did you go with the 1.6?
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Discretesignals
Ultimate Carjunky
/ Moderator
Sep 25, 2012, 5:36 PM
Post #13 of 66
(8707 views)
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Re: 93' K5 Blazer 5.7 TBI Cold start flooding issue
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If it is already running rich when it is warmed up, it is going to run even richer when it is cold. The computer is going to increase injector pulse width on a cold engine to act like a choke. I have a sneaky suspicion that your change in manifold pressure by changing the camshaft profile has affecting the way the computer is controlling the fuel and timing curve.
On a speed density fuel system, which yours is, the MAP sensor is used by the ECM to determine engine load. The ECM needs to know the engine load to calculate the fuel and ignition curve. Engine coolant temperature also plays a major role in how the ECM adjusts the fuel curve. Under heavy acceleration manifold pressure is high, so the ECM is going to be dumping fuel. If you have a worn out engine or a change in camshaft profile, that will affect engine manifold pressure. It will make manifold pressure high at idle and the engine will run rich. That is problem with changing air flow characteristics on a engine with a speed density system. It can be compensated for by changing the the ECM's look up tables which it uses to calculate the ignition and fuel curves.
It is really hard to diagnose your problem because the engine is modified and the fuel injection system and programming really hasn't been changed to match how the engine is modified unless the custom chip was tailored to how your set up.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Sep 25, 2012, 5:41 PM)
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nickwarner
Veteran
/ Moderator
Sep 25, 2012, 5:48 PM
Post #17 of 66
(8694 views)
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Re: 93' K5 Blazer 5.7 TBI Cold start flooding issue
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I wouldn't be surprised if the cam profile made it run rich and now has killed the cat. Could be an issue now. If I were you I'd be changing to the Edelbrock Performer cam with the intake profile for your TBI system. If the roller rockers are a 1.6 ratio I'd change to a 1.52 ratio.
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SuncrestSniper
User
Sep 25, 2012, 5:57 PM
Post #18 of 66
(8690 views)
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Re: 93' K5 Blazer 5.7 TBI Cold start flooding issue
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But why did it run fine all last winter without a hitch. We had nights in the teens here several times and it always fired right up. You never stated that. How is the wiring to your injectors. I've seen wiring get pinched in the spacer ring and cause the injectors stay on. When you turn the ignition on is there fuel leaking or spraying out of the injectors?
Sorry I thought in my first post that by me saying this started just recently made it clear enough. as for the injector wires they are clean and untouched. There's actually a notch in the TB with a rubber seal it's offset in the inside of the ring so the wires can't get pinched.
When in an hour I'll pull the cam specs and see what they tossed in.
SS
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Discretesignals
Ultimate Carjunky
/ Moderator
Sep 25, 2012, 6:01 PM
Post #20 of 66
(8686 views)
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Re: 93' K5 Blazer 5.7 TBI Cold start flooding issue
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Did you replace the injectors because of the flooding problem or did you change them for another reason? Would be interesting to see what the injector duty cycle is on this thing while it is flooding out. So hard to diagnose something like this without data.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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nickwarner
Veteran
/ Moderator
Sep 25, 2012, 6:03 PM
Post #21 of 66
(8685 views)
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Re: 93' K5 Blazer 5.7 TBI Cold start flooding issue
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Run overly rich or with misfire for too long and you are putting raw unburned fuel down your exhaust pipe and into your catalytic convertor. It overwhelms and overheats it until the catalyst becomes permanentely damaged and clogged, which will make it have major driveability issues.
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Discretesignals
Ultimate Carjunky
/ Moderator
Sep 25, 2012, 6:09 PM
Post #22 of 66
(8683 views)
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Re: 93' K5 Blazer 5.7 TBI Cold start flooding issue
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If it has the cat still on it. Running rich will foul out the O2 sensor also. Could make can make the O2 stick lean which means the computer will keep adding fuel making the engine run even richer when it is in closed loop. Normally a stuck o2 won't cause flooding during starting though and should set some sort of inactivity code in the ECM.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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nickwarner
Veteran
/ Moderator
Sep 25, 2012, 6:24 PM
Post #23 of 66
(8681 views)
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Re: 93' K5 Blazer 5.7 TBI Cold start flooding issue
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You are also running headers on this, and I imagine you arent using a factory downpipe. If you're running duals you have another issue altogether. Your factory exhaust had a y-pipe that came together to the right of the transmission and thats where the O2 is placed. If you only have the 02 in the one bank you are only sampling half of the exhaust and getting the wrong reading which is going to send the computer for a backflip.
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Discretesignals
Ultimate Carjunky
/ Moderator
Sep 25, 2012, 6:28 PM
Post #24 of 66
(8680 views)
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Re: 93' K5 Blazer 5.7 TBI Cold start flooding issue
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Not to mention the end of the world is coming in November, so we really have to figure this out before it is too late.....LOL
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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