3.2 hesitation from 3k RPM onwards

[GT2BH]

Car is a recently acquired 1986 3.2 euro (no o2) carrera.

I've searched and read many topics on this subject, but mine is a little bit different. I noticed this more after installing the SW chip. When I hit 3k RPM in 3rd, the car starts to hesitate under WOT, and same in 4th. it keeps accelerating, no problem, but it doesn't feel normal. It was very noticeable with the SW chip, and when I reinstalled the stock chip it got better but the issue is still there. I checked the usual culprits listed in other threads but no use. I was told the injectors might need cleaning.

The fuel quality setting was on 4, and I changed it to the 0 position. I am running 98 octane fuel. My chip was for 95 octane. Car is completely stock.

I'd appreciate any input.

[theiceman]

Well i dont have any input as to your particular issue , but i would suggest doing your troubleshooting with the stock chip . After you get it sorted then put your SW chip in.
BTW have you tried swapping out the coil ? sounds like its struggling under load and could be electrical also .
I assume you have done the routine stuff such as plugs , wires , fuel filter , checked centrifugal advance in your distributor ?

[GT2BH]

Originally Posted by theiceman

Well i dont have any input as to your particular issue , but i would suggest doing your troubleshooting with the stock chip . After you get it sorted then put your SW chip in.
BTW have you tried swapping out the coil ? sounds like its struggling under load and could be electrical also .
I assume you have done the routine stuff such as plugs , wires , fuel filter , checked centrifugal advance in your distributor ?

I removed the SW chip already and started the troubleshooting. I actually changed my coil to an MSD8222 I had belonging to my SC after I started this thread. There is some improvement and the hesitation isn't as pronounced, plus acceleration seems to have improved in 3rd and 4th.

The other stuff is all relatively new - plugs, wires, fuel filter, distributor etc.

I'm going to try pulling the injector wires tomorrow to see if its firing on all cylinders.

[scarceller]

Double check your ignition wires. Be sure none are loose on the spark plug. Also what are the plugs gaped at and what spark plugs?

Start with the ignition first but you also need to know what's going on with fuel in that problem area. You need to know what the AirFuelRatio is at during the problem conditions and you'll need a good Wide Band O2 system for this.

[Steve W]

Many imported ROW/Euro 3.2 are hack jobs modified in an attempt to pass Federal emissions regulations. Some were done correctly, some were never done, and many are horrible hack jobs with aftermarket piggyback 'fuel/air controllers', altered fuel quality switch settings, non functioning single wire O2 sensors, cheap restrictive aftermarket cats, and tampered air flow meters with tightened spring tension on the doors. Best is to revert and restore everything back to factory ROW specification. Check that there are no aftermarket boxes under the seat next to the DME, and no suspect wires cut into or dangling out of the harness next to it. Also check the silicone seal on the back plastic cover of your air flow meter to see if it has been opened and resealed before. Check if your DME ends in 050 (USA and had been replaced) or 051 (ROW - original).

If its not caused by a compromised spark because of faulty wires worn plugs/cap/rotor, then it may be a lean fuel issue caused possibly by the above or past alterations.

[GT2BH]

Originally Posted by Steve W

Many imported ROW/Euro 3.2 are hack jobs modified in an attempt to pass Federal emissions regulations. Some were done correctly, some were never done, and many are horrible hack jobs with aftermarket piggyback 'fuel/air controllers', altered fuel quality switch settings, non functioning single wire O2 sensors, cheap restrictive aftermarket cats, and tampered air flow meters with tightened spring tension on the doors. Best is to revert and restore everything back to factory ROW specification. Check that there are no aftermarket boxes under the seat next to the DME, and no suspect wires cut into or dangling out of the harness next to it. Also check the silicone seal on the back plastic cover of your air flow meter to see if it has been opened and resealed before. Check if your DME ends in 050 (USA and had been replaced) or 051 (ROW - original).

If its not caused by a compromised spark because of faulty wires worn plugs/cap/rotor, then it may be a lean fuel issue caused possibly by the above or past alterations.

Hi Steve

Seems like you encountered many hack jobs in your line of work!

I am based in the Middle East. My car is an original untouched euro version (which is what we get in the Middle East) from the local dealer. Full history at the dealer, completely stock. So we can set aside the hack job stuff and start looking at other options

I am getting the car serviced, along with new spark plugs next week. I am also receiving my wideband sensor next week so I'll be able to run some tests. I'll check the wires and make sure they're plugged in properly - seems like I didn't do that yet.

Edit: The issue happens when I accelerate from low RPM in 3rd - it starts at 3k RPM til 5k then goes away. Same in 4th.

[Tippy]

First thing I'd check is the WOT switch. It's a simple continuity test. The fuel map might be fat enough after 5k to run good enough and 3-5k be too lean even though WOT fuel map is not triggered.

[ischmitz]

Since your car doesn't have the O2 closed-loop taking care of the A/F mixture in part throttle it solely relies on the maps in the chip and sensor inputs for an accurate mixture. First I would baseline everything on the stock chip. Ensure common maintenance issues are been taken care of (air filter, fuel filter, valves, etc.) if you don't have a history. Next, check the items that impact mixture. Several items come to mind:

- CHT sensor: it should be a two-wire and make sure it checks out against WSM specifications

- fuel pressure: check that the pressure regulator properly reacts to intake manifold pressure changes. The fuel pressure needs to rise when the intake pressure goes up (opening throttle)

- Vacuum leaks: Check the common areas causing vacuum leaks in the intake tract, gaskets between heads and intake runners, rubber hoses on intake track, boots, etc.

- AFM: make sure there are no "dead spots" when the flapper moves through its range. There is a test outlined on FRWilke's website with a 9V block battery and a voltmeter.

- injectors: could be leaking or having poor spray pattern depending on history

Best,
Ingo

[mnez]

I chased a rpm specific misfire in my Carrera for a long time - felt like a rev limiter cutting in.
It turned out to be failing connector. The 4 pin connector on the firewall had one loose pin that powered the RS injectors.
The shop serviced the connector, and used a zip tie wrapped around the connector to keep it tight. No issue since.
Worth checking for good connections everywhere.

[scarceller]

Having the problem in WOT from 3000-5000RPMs is a red flag on ignition. This RPM area is where this engine is most efficient and achieves hi-cylinder pressures and under hi cyl pressure is also the most difficult time for spark to jump the spark gap. Any of these could cause misfires under these conditions:
- spark gap is to wide >1.0mm
- plugs are shot
- you are using some non stock plugs (never use multiple tip plugs like Boch2 or Bosch4)
- ignition energy is compromised (weak coil or non stock coil that's not fully charging)
- bad plug wires that are cracked allowing spark to jump to ground
Keep in mind that the spark energy is looking to spark at the point of weak resistance, under normal conditions it sparks at the gap in the plug but as cyl pressures rise this gap gets more and more dense and the resistance starts to rise, it's under this condition that the spark MAY find a better (less resistance) path along the wire and simply jump from the wire to some better ground point.
Bottom line: inspect and verify the cap, rotor, wires and plugs. You can also narrow the plug gap slighty to say 0.5mm instead of the stock 0.7mm to see if that helps. But first verify what the spark plug gap is at now. It should not be >1.0mm and better yet it should be at spec 0.7mm

[GT2BH]

I checked the wires - checked the CHT - did the AFM mod - car runs better but still has the hesitation. I also noticed that the first time I apply full throttle in any gear after starting the car cold it would smoke for a bit and then it won't smoke again until the next day.

[scarceller]

I'm not sure what you mean WOT after cold start? Do not do any WOT pulls till the motor is fully warm. Are you saying that it smokes under WOT after fully warm but only on the first WOT pull?

[GT2BH]

Originally Posted by scarceller

Are you saying that it smokes under WOT after fully warm but only on the first WOT pull?

Bingo

Thinking about putting the fuel quality setting on 3 and checking the car (3% lean std)

[MConn]

I think the ground for the spark plugs goes through the ground strap under the car from the transmission to the body. Cleaning it won't hurt anything.

I'm jealous of the 98 octane, we only get 93 around here.

Mike

[GT2BH]

Checked the rechecked everything and can't find fault. I will remove the distributor cover today and reattach it and see if it makes a difference. I will also inspect the firewall connector and wot switch. I have a track event tomorrow so I hope I can fix it.

When I removed the plugs, cyl 1 plug was black with soot. The rest were OK. I changed from Mobil 1 synthetic oil to Royal Purple HPS. The plugs are original factory plugs properly gapped.

[GT2BH]

OK - I rotated the wot switch fully clockwise and it seems to have fixed (or improved) the problem. Didn't feel hesitation and the car is definitely more lively!

Will reinstall the chip later today and put the fuel quality setting back to 0.. wish me luck

[Tippy]

OK - I rotated the wot switch fully clockwise and it seems to have fixed (or improved) the problem. Didn't feel hesitation and the car is definitely more lively!



Will reinstall the chip later today and put the fuel quality setting back to 0.. wish me luck

Score. Do I get a prize? J/K

[scarceller]

Originally Posted by GT2BH

OK - I rotated the wot switch fully clockwise and it seems to have fixed (or improved) the problem. Didn't feel hesitation and the car is definitely more lively!

Will reinstall the chip later today and put the fuel quality setting back to 0.. wish me luck

After you rotate the switch you should verify at what throttle angle it closes. It's easy to do with a simple 12vdc test light. Here's how:

- No need to even put key in ignition
- Clip one end of the test light to a fuse in the rear fuse block, they all should have 12vdc. At this point one end of the test light has 12vdc.
- Pull back the rubber boot of the WOT switch harness but leave the harness connected to the switch.
- Now poke one of the wires in the harness, pick one then try the other wire. One of the wires will light the light and this wire is the ground side to the switch.
- The other wire that does not light is the wire that feeds the DME the WOT signal. Leave the light connected to this wire (light is out at this point)
- Now start opening the throttle and at about 80-90% throttle the light MUST come on. The point where the light comes one is when the WOT signal is sent to the DME.
- Rotating the switch alters the throttle angle for WOT activation point.

This test also fully tests the switch with it connected.

Hope that helps.

[GT2BH]

Originally Posted by Tippy

Score. Do I get a prize? J/K

Originally Posted by scarceller

After you rotate the switch you should verify at what throttle angle it closes. It's easy to do with a simple 12vdc test light. Here's how:

- No need to even put key in ignition
- Clip one end of the test light to a fuse in the rear fuse block, they all should have 12vdc. At this point one end of the test light has 12vdc.
- Pull back the rubber boot of the WOT switch harness but leave the harness connected to the switch.
- Now poke one of the wires in the harness, pick one then try the other wire. One of the wires will light the light and this wire is the ground side to the switch.
- The other wire that does not light is the wire that feeds the DME the WOT signal. Leave the light connected to this wire (light is out at this point)
- Now start opening the throttle and at about 80-90% throttle the light MUST come on. The point where the light comes one is when the WOT signal is sent to the DME.
- Rotating the switch alters the throttle angle for WOT activation point.

This test also fully tests the switch with it connected.

Hope that helps.

Great info - I'll try to test it out and post the results

[Tyson Schmidt]

Just want to mention that you should remove the distributor cap and make sure the mechanical advancer for the ignition rotor is working.

If it is frozen, then as the computer advances the timing, the rotor is pointing between the two poles inside the cap, instead of right in line with the correct one for that cylinder.