TeamCapri

Tech, Repairs, Upgrades => Capri XR-2 89-94 => Topic started by: SuperSport346 on July 25, 2012, 02:34:00 PM

Title: Misfire Under Heavy Acceleration
Post by: SuperSport346 on July 25, 2012, 02:34:00 PM
My 91 XR2 has what seems to be a misfire that only occurs under hard acceleration, i.e. merging on the highway.  Misfire occurs at >3000rpms.  It doesn't seem to misfire in first gear, maybe only under boost?  It didn't seem to have a problem before I replaced my turbo.  I've also found oil in the intake hose if that's any help.

Other than under hard throttle, it runs like a dream.  I threw new plugs and wires at it with no avail.   :(    I appreciate any help!
Title: Misfire Under Heavy Acceleration
Post by: SuperSport346 on July 26, 2012, 02:15:00 AM
Driving around this morning I noticed two things.  First, the "misfire" occurs only when I'm pushing about 10 psi of boost.  Second, the car beeps at me right before it happens.  This makes me believe that it isn't a misfire, but something related to the turbo.  Any ideas?
Title: Misfire Under Heavy Acceleration
Post by: tonlaw71 on July 26, 2012, 03:05:00 AM
Yep, you're overboost sensor is kicking in. The beep is the overboost warning signal. Do you have a boost controller installed? If so, you either need to turn down the boost, or disconnect the overboost sensor. If you disconnect the sensor, make sure you don't go above about 11psi unless you have a chipped ECU.
Title: Misfire Under Heavy Acceleration
Post by: SuperSport346 on July 26, 2012, 03:36:00 AM
As far as I know, I do not have a boost controller or chipped ECU.  What is my easiest/cheapest option here?  I doubt I would be able to stay under 11psi if I just disconnescted the sensor.
Title: Misfire Under Heavy Acceleration
Post by: tonlaw71 on July 26, 2012, 03:50:00 AM
Then I'm not real sure why you're overboosting. Did you replace your turbo with another stock one? Was the replacement rebuilt, or off a running motor? The least expensive way to go to control the boost is to get a manual boost controller. Get a decent ball and spring controller. You can get them for around $20 on ebay.
Title: Misfire Under Heavy Acceleration
Post by: SuperSport346 on July 26, 2012, 04:01:00 AM
I was told it was a stock turbo although I'm not sure the guy I bought it from knew all that much about it.

I will look into one of those boost controllers, are they difficult to install?
Title: Misfire Under Heavy Acceleration
Post by: Rocketman on July 26, 2012, 04:05:00 AM
They're very easy to install. You need to do a few supporting modifications with it, though.

How much boost are you running currently?

Are you running premium fuel? Where is your ignition timing set? Does the engine sound like it's detonating?

Is the oil there from the old turbo? Did you clean out the intake hoses/intercooler when you replaced the turbo? Engine oil in the intake air will lower the octane of the gas and cause problems
Title: Misfire Under Heavy Acceleration
Post by: tonlaw71 on July 26, 2012, 04:10:00 AM
Nope, super easy. Do a search on here or on the Facebook pages for details. The easiest place to install it is in the hose going from the crossover pipe to the waste gate. Takes about 5 minutes. Also, I was thinking your waste gate may not be opening when it should which could be causing your over boost issue. Did you check the actuator rod before you installed the new turbo to make sure it was moving? If that is the problem, a boost controller won't help.
Title: Misfire Under Heavy Acceleration
Post by: tonlaw71 on July 26, 2012, 04:16:00 AM
Yeah, forgot to mention that about the oil. Very important to clean out the intercooler and pipes. Do you think it could be the waste gate, Matt?
Title: Misfire Under Heavy Acceleration
Post by: SuperSport346 on April 29, 2013, 12:41:00 PM
Can somebody link me to a thread with pics/instructions on how to install a boost controller?  I installed one per the manufacturer's vague instructions, and it did not solve the problem.  I tried searching with no luck yet.

I have not checked the actuator rod on the turbo.  Can it be moved by hand while installed?

I think the oil is left from the old turbo.  I haven't driven the car a whole lot since the new one was installed.
Title: Misfire Under Heavy Acceleration
Post by: SuperSport346 on April 29, 2013, 12:52:00 PM
Ok, I installed it where it is indicated in this picture, where another member recommended install.

  (http://s7.postimg.org/wumbejtgr/capri_engine.png)

I turned it all the way down per manufacturer instructions, and the overboost controller still kicks in around 8-10psi on the stock gauge.  I know stock gauges aren't the most accurate, but I don't want to spend the money on an aftermarket one at the moment.

What "supporting modifications" should be done, rocketman?

The MBC instructions said to disconnect the stock system, which I did not do.  I'm not finding anything about doing that here on the forum.  Maybe that will solve the problem?  I don't want to take any risks though...
Title: Misfire Under Heavy Acceleration
Post by: Gostlrs on April 29, 2013, 04:40:00 PM
What MBC did you get, Some are crap.

To see if you might have a boost leak or if the wastegate / MBC is bad do this.

Take the vacuum line from the boost source (your red arrows) to the wastegate. Run it. should only be 5-7psi. If it goes higher, then you have either a boost leak somewhere or the actuator is not opening.

So if that is good...you can assume that your MBC is bad or you don't have it set up correctly.

   (http://www.turbosmartusa.com/wp-content/uploads/2011/10/5483.jpeg)

That is how it should look set up.

You need a gauge if you are going to raise the boost. They are cheap. You can get a manual sunpro one for 20-25 bucks.

The boost cut is located here. Unplug it.
   (http://www.werbatfik.com/img/ecu/boostcut3.jpg)

I would not do that until you get your boost gauge & you know your boosting a steady 7-8 psi every time.

You can run about 9 psi without the rocketchip & up to 12 with it installed.
Title: Misfire Under Heavy Acceleration
Post by: Gostlrs on April 29, 2013, 04:45:00 PM
If you have this style, they are crap IMO & I have never had one work right.

   (http://alscomputerltd.com/yahoo_site_admin/assets/images/boost.291225819_std.jpg)


This guy here is a member and sells them.
 http://tunerfixx.com/store/index.php?main_page=product_info&products_id=1 (http://tunerfixx.com/store/index.php?main_page=product_info&products_id=1)

or

I been using this lately on my boosted cars.
 http://prosportgauges.com/manual-boost-controllers.aspx (http://prosportgauges.com/manual-boost-controllers.aspx)

Love it, small, looks nice, cheap, good warranty & love their Evo Series Gauges too.
Title: Misfire Under Heavy Acceleration
Post by: Rocketman on April 29, 2013, 06:18:00 PM
Whoa there Jamie, I missed something early in this thread. This is not a boost controller issue, it's a boost creep issue.

You're experiencing boost creep for some reason, do you have a large exhaust installed? If not, it could be an issue with the wastegate, vaccum/boost reference issue, etc.

A boost controller will only raise the boost level above the baseline boost, it will not lower it at all. If you're overboosting without the controller, it's not going to help.

I would STRONGLY RECOMMEND leaving the boost cut switch connected until you sort out what is causing the boost to creep that high.
Title: Misfire Under Heavy Acceleration
Post by: Gostlrs on April 30, 2013, 06:59:00 AM
That is why I said to run it without the MBC. It will give him a idea of what his problem is. If everything is steady without the MBC installed. Then the MBC is the issue.

If it still hits boost cutoff then yes, he has a issue. Boost leaks, bad wastegate, ect.....
Title: Misfire Under Heavy Acceleration
Post by: Chicken on April 30, 2013, 07:45:00 AM
Double check that the boost gauge you are using is accurate.

The stock XR2 gauge in the dash is not known to be extremely accurate.

The overboost module is suprisingly reliable.

The "misfire" may be the overboost module working properly. Some units activate btween 11 and 12 psi.

A "boost controler" can increase the the surge wave and the top pressure of this surge will trip the overboost cut.
Title: Misfire Under Heavy Acceleration
Post by: Gostlrs on April 30, 2013, 07:51:00 AM
I think we all agree he is hitting the boost cut & that the dash gauge is crap...LOL
Title: Misfire Under Heavy Acceleration
Post by: SuperSport346 on April 30, 2013, 12:56:00 PM
I bought a Voodoo MBC, and only to lower the boost.  I'm not interested in raising it.

I agree that the stock gauge is probably not right, and that the overboost module is doing it's job.  I just need to find out why.
Title: Misfire Under Heavy Acceleration
Post by: Gostlrs on April 30, 2013, 03:18:00 PM
Then you need to do what I said & it will get you in the right direction.

Run the vacuum line from boost source to the wastegate. If you are still getting boost cut then you have a boost leak or the wastegate could be bad.


Creep is when you hit the set PSI & then it will slowly raise while under boost. The way you explained it I don't think it is a creep problem.


You can check the wastgate by applying vacuum to it, increase it 1 psi at a time. and see when it actuates.

Check all your hose connections. A leak tester can be made cheap.

My last Capri was hitting boost cut from the time I bought it. Ended up being that the PO had all the vacuum lines routed incorrectly. Not sure if you just got this or it just started happening.
Title: Misfire Under Heavy Acceleration
Post by: SuperSport346 on April 30, 2013, 04:15:00 PM
It started happening when I installed a used turbo.  My old turbo hadn't grenaded yet, but had significant shaft play.  It would boost however, and it never cut off, but I'm not certain it boosted as high as this new one.

Could I have mixed up a line re-installing the turbo?

You said to run the vacuum line from the boost source (the red arrows in my pic) to the wastegate, right?  That is how that line was run, and I just spliced into it for the MBC.
Title: Misfire Under Heavy Acceleration
Post by: Rocketman on April 30, 2013, 04:44:00 PM
Remove the boost controller for now, if you can replace the whole wastegate line there with new hose & see if that makes a difference

When you installed the turbo, did you connect the wastegate arm to the lever on the turbo's hot side? there's a c-clip or e-clip that retains it

Run some regulated (no more than ~15-20psi) compressed air into the wastegate line, see if you can watch the actuator rod moving properly
Title: Misfire Under Heavy Acceleration
Post by: Gostlrs on April 30, 2013, 05:38:00 PM
Running the line straight from the boost source to the wastegate will make the car boost at wastegate pressure.

So that is why if your car still overboost when it is set like that you have a leak, or wastegate problem.

You have the old wastgate that you can swap back in if it still overboost.
Title: Misfire Under Heavy Acceleration
Post by: SuperSport346 on May 30, 2013, 05:19:00 AM
Well I just ended up taking it in to a shop that specializes in turbo'd cars.  He just called and informed me that it is the boost solenoid not working.  I plan on pulling the one off my old turbo (which never had this problem) and having them install it.

Hopefully this gets the problem taken care of, I will be glad!
Title: Misfire Under Heavy Acceleration
Post by: Rocketman on May 30, 2013, 11:32:00 AM
Boost solenoid... the "Wastegate"? The Capri does not use a "Boost Solenoid"

Either way, hope that'll solve the problem
Title: Misfire Under Heavy Acceleration
Post by: Gostlrs on May 31, 2013, 03:15:00 AM
I bet they did what I said....LOL
Title: Misfire Under Heavy Acceleration
Post by: azgtx on June 01, 2013, 03:33:00 AM
You say you replaced the turbo...but with what? Is it another VJ14 or by chance does it have a bigger compressor? Did you swap over your old wastegate accuator or use the one on the replacement turbo?Just wondering...everything worked before the swap so there is where your issues started. Should be easy to find.
Title: Misfire Under Heavy Acceleration
Post by: SuperSport346 on June 04, 2013, 01:25:00 AM
They are telling me it's a boost solenoid, not the waste gate.  They're telling me that whatever they're referencing shows a boost solenoid on these cars.

This is supposedly a stock VJ14 I purchased on another forum.
Title: Misfire Under Heavy Acceleration
Post by: SuperSport346 on June 04, 2013, 01:29:00 AM
I did not swap the wastegate actuator off the old turbo.  If there is no boost solenoid on these cars, then I'm thinking that the actuator must be the problem and I'll probably have them swap that (or I'll just do it myself).
Title: Misfire Under Heavy Acceleration
Post by: Gostlrs on June 04, 2013, 01:04:00 PM
I wonder if they are talking about the Overboost one. That is doing its job & preventing you from overboosting.

You have a Manual boost controller. Do what I said and report back. It will tell you what the problem is!
Title: Misfire Under Heavy Acceleration
Post by: SuperSport346 on June 05, 2013, 01:30:00 AM
What you said to do was run the vacuum line (the one pointed out by the red arrows in that picture I posted) straight to the wastegate actuator, correct?  Unless you're telling me to remove the MBC I installed on that line, that is how that line already runs.  The MBC is already removed.  I had the problem prior to installing it and at it's lowest setting it did not eliminate the problem, so I removed it.

I'm pretty certain the wastegate is sticking or opening late and the guy at the shop is wrong.  He told me that all of the lines are run correctly, which I believe to be true.  Searching the service manuals over at techcapri I cannot find anything about a boost solenoid, so I'm not sure where they ever got that idea.
Title: Misfire Under Heavy Acceleration
Post by: Gostlrs on June 05, 2013, 03:00:00 AM
Yes, run the line from that red arrow to the wastegate. If the car is still overbooting then you have either a boost leak or the wategate actuator is bad.

Assuming all the other vacuum lines are correct as you believe.
Title: Misfire Under Heavy Acceleration
Post by: SuperSport346 on June 05, 2013, 03:52:00 AM
What might cause a boost leak and how could I check for one?
Title: Misfire Under Heavy Acceleration
Post by: Gostlrs on June 05, 2013, 04:08:00 AM
You can make a cheap tester. Google it, can be made with Home Depot things for like 10-15 bucks. You tube videos will show you want to do.

Basically its a leak of the intercooler lines. Maybe even a vacuum leak as well. Can be a bad intercoller, couplers, throttle body, intake manifold. seen all leak.
Title: Misfire Under Heavy Acceleration
Post by: SuperSport346 on June 21, 2013, 06:26:00 AM
Well I didn't get right back to updating this, but the Capri is running just fine now.  The shop did a boost leak test and re-checked the wastegate.  They attempted to remove it to install the wastegate off the old turbo, but said they couldn't do it without removing the turbo, which I wasn't going to pay them to do.

I took the car home, and decided to drive it to work the rest of the week, and I'll be damned if it didn't start working like it should.  The wastegate must have been sticking, and they got it to open without realizing it.
Title: Misfire Under Heavy Acceleration
Post by: Rocketman on June 21, 2013, 02:31:00 PM
Glad it's running good, thank you for the update! Hopefully no more issues.
Title: Misfire Under Heavy Acceleration
Post by: Gostlrs on June 23, 2013, 12:00:00 AM
Cool
Title: Re: Misfire Under Heavy Acceleration
Post by: Jim Simms on January 03, 2014, 03:21:45 AM
The original question seemed to be misfire at hard acceleration, maybe 3000rpm.
I am no mechanic, and defer to Russ and others, but I had the same problem for a couple of years. The car would hesitate and jerk a bit as I was accelerating, mostly in 5th gear. My remedy? I started changing out vacuum hoses, beginning from the carbon canister on the passenger side firewall, and worked my way to the driver side. Be very careful as you disconnect the hoses. Some of the parts are plastic, and I did break off the end of a solenoid (Russ got me another). I replaced about 5-6 hoses.  The problem ended. I never knew which hose was causing the problem.