RJP 951

Danno,

I installed the chip kit (DME v8c) and new FPR this morning, and something is terribly wrong. I took the car out for a test drive and it seemed OK at first, but once the engine warmed up it was really running poorly.

Symptoms:

1) Around 3000 RPM the engine starts stumbling, and at 3500 - 3800 it bogs down as if there is no power at all. This occurs even under light acceleration. Under heavier throttle, it will intermittently "catch" and surge ahead for a moment and then bog down again.

2) The idle seems fairly steady, but there are blips that sound like it's missing a beat every now and then.

3) The engine is backfiring after letting off the gas. This is something I've never heard it do before.

I recently replaced all vac lines and hoses, and installed a boost gauge. I've driven the car since these were put in and it ran better than it ever has before. I also have an A/F meter that I connected today inside the DME harness connector per the instructions on your Web site. It seemed to be operating normally at first but showed no reading at all once the car started running like this.

I checked for obvious physical problems with connections and the new FPR, etc., and no sign of a problem.

[EDIT] As I checked out the connections around the DME and KLR I noticed the black bracket and the DME box were quite warm, but I don't know if that's normal. I also just re-started the car and the AF gauge was operating normally again.

What should I do?

Thanks in advance for your help!
Ron

Ski

Not to butt in here,,,One thing I have seen Danno reply to people on is about making sure you have the correct colored wire connection in the harness. Some wires in the DME harness can be deceiving on color code; i.e. green with red stripe vs red with green stripe. Ask me how I know......

Double check your wiring again on the A/F gauge or disconnect it altogether to see if that is the problem. Good luck.

Danno

Hmmm, I think the part about the car stumbling once it's warmed up may be related to the DME overheating.

Backfiring is usually a sign of too-rich a fuel-mixture. I take it you're running stock injectors, so even if you have the chip's injector-size selections set to the wrong size, you'll only get leaner mixtures, not richer.

Make sure you have the vacuum line on the FPR hooked up and there's no leaks anywhere. It reduces fuel delivery in off-boost operation such as idle and cruising around.

I'll check the mappings on the chip I sent you to make sure there's no strange richness dialed in anywhere.... I don't think so though....

silicondigital

Also somebody said they kinked the line to the KLR and didnt notice it on the map install until later. Also make sure you did'nt pull that line out of the manifold or something.

RJP 951

I took the car out again tonight and it displayed exactly the same symptoms... started out fine, but once thoroughly warmed it ran terrible. By "warmed up" I'm talking about a good 15 minutes or so with no apparent problem.

Once the problems began I cut the sender wire to my A/F gauge just to rule that out, and it made no difference.

I also checked for kinks in the KLR line and it seems fine. So is it's fitting at the KLR box.

All the vacuum lines and hoses under the hood were replaced a few months ago with all new clamps, tees and elbows. I'm getting full boost when it's running correctly.

Danno, in reply to your note:

- the FQS switch is set to #0.

- the main change in the idle once warm is that there's an occasional stumble.

- once the car starts running rough, it is very difficult to get the car past 3500 rpm at all, though it will surge ahead and through the 4000 range inconsistently.

- The sensation on acceleration is like pressing the gas but nothing happens, then bogs down, and then may surge ahead but sporatically. The "nothing" and bogging occur both under vacuum and boost. When the surging occurs the reading on my boost gauge is very jumpy, perhaps as if the wastegate is being opened/closed rapidly?

- The vacuum/boost lines appear OK, including the banjo connection for the KLR that's on the intake manifold. I also checked to ensure the line to the wastegate was secure, and it is. This is also a new hose with new clamps, and they're secure.

- The backfiring gets pretty severe. I noted some both on acceleration and when downshifting.

Last but not least, I looked under the hood when I parked the car and saw that MY HEADERS ARE GLOWING RED HOT! I tried to take a picture but in the dark it didn't show up, and with a flash it floods out the glow. The hottest areas appeared to be the "accordian" sections near the top, and the joint at the downpipe, if I was seeing correctly.

While I was out I'd made a few stabs at the throttle in third gear (no more than a few seconds at a time, just to see if I was getting full boost). Otherwise I didn't drive hard in any way.

I'll try putting the original DME chip back and see what happens (I wish I hadn't reassembled everything!) It's supposed to be a decent day here again tomorrow, so if you have anything else I can test or observe while the roads/weather permit, please let me know!

Thanks
Ron

tecart

what you need to do is take the converter pipe off at a muffler shop, take a flashlight and look inside the pipe, i will bet your converter is plugged up, ask the mechanic to let you see into the pipe once its off, it should be hollow and sortof open in the middle with honeycome mesh looking inside, see if anything falls out by tipping the pipe onto the ground in both directions, then reinstall and your power will be back, im only 50% sure this is your problem, let us know

tecart

woops i saw you reported the headers as red hot, now im 75% sure your cat pipe is clogged up, let us know

silicondigital

If its not your cat clogged up. Maybe you put the chip for the KLR in the wrong way and your KLR is sending some BS to the dme, and its still running because your DME is fine, but retarding the **** out of your timeing off the scale, or rich off the scale or something? Glowing headers shows incomplete combustion either way way to rich or way late ignition. Makes sure you have the harness for the KLR and DME both cliped in tightly and look for any wires that may have gottne pulled out of the harness. It might very well be a block in your cat and the wastegate opening and closeing letting pressure out might be causing the surges. I dont know just some thoughts.

Danno

"When the surging occurs the reading on my boost gauge is very jumpy, perhaps as if the wastegate is being opened/closed rapidly?"

Ok, this is a clue. Make sure you have your ReliaBoost installed with the knurled adjustable end at the outlet going towards the wasteagate. You might want to adjust it to give you 10-12psi max-boost to be on the safe side. Glowing red-hot headers is a normal occurence actually, just give your car more cooldown driving before you stop.

To further troubleshoot, swap out one chip at a time and compare these two configurations:

1. GURU DME and old KLR
2. old DME and GURU KLR

This will tell us if it's the DME or KLR chip that's causing your issues. I don't think we're sending out bad chips anymore with our new programmer and new batch of chips.

Finally, a remote possibility exists of the incorrect ignition map being selected. As a test, cut the brown/blue-stripe wire coming out of the DME and see if that helps. This is the altitude-sensor line, but I've seen a couple of them fail in a state that makes the DME select an alternate ignition map.

RJP 951

I'll try the chip swaps today. I did check several times to make sure both chips were inserted correctly before I closed up the boxes.

I've had the Reliaboost installed for several months and I verified it was correctly installed back when other folks were having problems with this. I'll triple check to be sure, and I'll turn down the boost for now.

If I cut the line to the altitude sensor is this something that can remain disconnected? There's not a bunch of slack in those wires to allow for repair!

Thanks all for your suggestions. I'll report back more findings later today.

Ron

RJP 951

Well, 4+ hours and 110 miles of testing later... I'm convinced there's a problem with the new chips (KLR at least, if not both). Actually I'm relieved that it doesn't appear to be something else!

Here's what I did and found:

- Opened up the ReliaBoost by 4 full turns to ensure I was at/near stock boost levels.

- Removed and reconnected the DME harness to verify it was properly seated. Also noted that the dielectric grease I'd applied on the connector left an even pattern showing proper contact on each blade of the DME side of the connector.

- Ran the following chip combinations:

STOCK DME and GURU KLR - Smooth operation without hesitations. However, it ran in "limp" mode, limiting boost to 1.2 bar (~3 PSI on my gauge).

STOCK DME and STOCK KLR - Smooth running with boost at normal 10-12 PSI range depending on gear.

GURU DME and STOCK KLR - Fairly smooth running. Felt strong/consistent except mild hesitations through the 3000-4000 RPM range.

GURU DME and GURU KLR - Started out OK but after several miles it starts acting up again. Idle got to be very rough, and strong hesitation and bogging. I was near home when this started so I didn't drive it for an extended period to see if it would start backfiring.

After the above tests I reconnected my A/F gauge to see if it induced any problems. I put the STOCK KLR back in, and the performance was as described above (EDIT: as described above for GURU/STOCK combination). The A/F gauge operated normally and showed a slightly rich mix in the 4000-4500 range.

I then reinstalled the STOCK DME (now running STOCK/STOCK again), and it again provided the best combination of smoothness and overall operation. The A/F gauge showed a similar richness in the 4000-4500 range, which I assume is due to the 3.0 FPR.

Other observations:

- The GURU KLR chip has a label with DME printed on it, but "DME" has been scribbled out and "KLR" hand-written on it. Maybe not important, but perhaps it helps narrow in on what batch of chips this was sourced from.

- It took a while for the GURU's to start acting up, but the engine was warm the entire time. I ran the tests back to back and followed the same circuit and driving pattern for each run, once the car was up to operating temp. Could the GURU chips be more sensitive to the physical temperature inside the DME/KLR boxes? I noticed that the DME box was warm whether the chip is stock or the GURU version. I assume this is normal?

Danno, for now I'm going to keep the STOCK/STOCK configuration until I hear back on how you think we should proceed. The only thing I haven't done is cut that wire you mentioned. I'd rather not do this if you're convinced the chips are at fault.

Thanks in advance for your help.
Ron

Danno

Ron, I think I can rule out the code in the chips. I checked them with some backups and the images on the HD haven't been corrupted or anything. Also your test seems to indicate everything works OK initially. It's this time-delay for the onset of the stumlbing that has me thinking that it's a physical problem with the chips heating up then failing; once they cool down, the next run is OK until they heat up again. So when I test out your replacement chips, I'll make sure to let it run for quite a while to ensure they don't overheat and fail.

RJP 951

Thanks Danno.

Let me know what you find and when you'll be sending out the new set. We had a new blast of snow and cold come in yesterday but I'm hoping for another brief warm-up so I can be back at it this weekend.

Thanks
Ron

michaeldean

I think I might have a similar problem. My 951 has the Guru chips, 3.0 bar FPR, wastegate shims and the reliaboost valve.

With stock DME & KLR chips, it runs & revs smoothly. Historically, I have had problems with the Guru chips – mostly involving misfiring/clattering at 4000 rpms. Danno sent me the new v8 chips which I tried last weekend. Initially all was well & the car felt much faster, smoother though I did not have an opportunity to really test the car at full boost. About 40 miles later, I did floor the throttle and immediately the staggering/hesitation returned. On my car, the onset of this is so severe that I can hear a clattering inside the engine somewhere and it always happens as I approach 4K revs. I have been through many sets of Guru chips and this last set performed the best - though it was not very long lived. When reverting to the stock DME chip, the problems always go away.

Danno, any ideas - I don't want to hijack Ron's thread here but maybe we have the same problem? Is this heat related?

Cheers,
Michael
1986 951

RJP 951

Michael,

If I recall correctly my problem also seemed to begin once I started to "accelerate agressively". Once the symptoms appeared, they could be observed anywhere from 2800 - 4000+ rpm, and regardless of how easy or hard on the throttle. At times these symptoms were downright scary.

Danno,
Any update on testing or observations at your end?

Thanks
Ron