Engine detonations - poor or rich fuel mixture?? - Alfa Romeo Forum
You are currently unregistered, register for more features.    
 
  Home Forums AO Club Member Gallery Classifieds Trade Directory  

Go Back   Alfa Romeo Forum > Supported Alfa Romeo Models > Technical & Vehicle Assistance > Alfa 147, 156 & GT

Reply
 
LinkBack Thread Tools
  #1 (Post Link)  
Old 28-06-08
FERRARIST's Avatar
Status: FERRARI FAN
Newbie
 
Join Date: May 2008
Location: Bulgaria
County: Stara Zagora
Posts: 29

Member car:

156 2.0TS - 2.5 V6

Engine detonations - poor or rich fuel mixture??

What causes detonations in inlet collectors?
Poor or rich mixture....or both can do it.I'm still have some bang-bang when start cold engine, and i'm concerned about.
Here you can hear sound of my engine, started cold in the morning, and no touch of the throttle.
http://hitspaces.net/engine.wma
To explain what do you hear - when engine is on, revs are 600 - 800 and it seems like it will die instantly - this continues 10 - 20 sec.(you may hear first bang on 22 sec of this record) and then it's OK - 1100 - 1200 rpm, and working perfectly.
More - when i start cold engine and shut it down immediately after starting, and repeat this 2-3 times, on the 4 starting it's OK....no detonations. My fuel tank cap is not original, and there is no pressure in the tank at all, and i know that there must be some. Can this be a problem?
I changed 8 new Denso iridiums.New Bosch MAF and lambda!!!! No change.......
Thanks.
Reply With Quote
Sponsored Links
Advertisement
 
  #2 (Post Link)  
Old 04-08-08
MattyR's Avatar
Status: -
Newbie
 
Join Date: Jun 2006
Location: Perth, Australia
Posts: 26

Member car:

99 Spider TS/04 GT V6

Re: Engine detonations - poor or rich fuel mixture??

i also get this with my car and would liek to know the solution?
Reply With Quote
  #3 (Post Link)  
Old 05-08-08
FERRARIST's Avatar
Status: FERRARI FAN
Newbie
 
Join Date: May 2008
Location: Bulgaria
County: Stara Zagora
Posts: 29

Member car:

156 2.0TS - 2.5 V6

Re: Engine detonations - poor or rich fuel mixture??

TRy to measure fuel presure when engine's cold......
Reply With Quote
  #4 (Post Link)  
Old 05-08-08
ALFAPAT's Avatar
Status: -
Club Member
Membro Premio
 
Club Member Number: 237
Join Date: Nov 2001
Location: United Kingdom
County: Moray
Posts: 1,763
Images: 6

Member car:

147 2.0l 156 jts 164 3l

Re: Engine detonations - poor or rich fuel mixture??

I think you may find this is your pre-cat sensors if your car has the twin cans at the manifold outlet, your lamdas there are faulty.
Reply With Quote
  #5 (Post Link)  
Old 06-09-08
Phil13's Avatar
Status: -
AO Member
 
Join Date: Nov 2006
Location: FRANCE
Posts: 54
Images: 16

Member car:

156 2.5v6 2000

Re: Engine detonations - poor or rich fuel mixture??

and what did you have to change ?
Reply With Quote
  #6 (Post Link)  
Old 06-09-08
jason156's Avatar
Status: only got a renault truck
AO Silver Member
 
Join Date: May 2007
Location: United Kingdom
County: Powys
Posts: 3,013
Images: 10

Member car:

Yella Stilo 3dr 1.9 JTD

Re: Engine detonations - poor or rich fuel mixture??

When my old 'vette was fireing on the inlet side it was caused by the cams on the exhaust side wearing and refusing to let gas out, which then burst out of the carb. very dramatic
It could be a timing issue..Jumped a tooth on the t belt?
Hope you get it fixed
Reply With Quote
  #7 (Post Link)  
Old 09-05-09
oem's Avatar
oem oem is offline
Status: -
Newbie
 
Join Date: Feb 2009
Location: Bulgaria
County: Veliko Tarnovo
Posts: 17

Member car:

Alfa 156 1.8 Twin Spark

Re: Engine detonations - poor or rich fuel mixture??

Hello. I have exactly the same problem with my alfa 156 1.8 TS. When the engine is cold it works with large explosion. Boom in the inlet manifold and does not to press the gas pedal. Same sound as the sound file from the first post. When trying to run the engine first started working, he's in 1000 rpm and immediately stops. Run it a second time. Works with 1200 rpm and started banging and ringing of the impoverished fuel mixture. While working as idling engine speed fluctuate. It lasts about 30 seconds. Then the sound of the engine is quiet and everything is fine. I checked the following and are in compliance.

1. Throttle position sensor
2. Mass Air Flow Sensor
3. Coolant Temperature Sensor
4. New Denso Iridium Power Spark Plugs
5. Ignition coils - working perfectly
6. Fuel pressure 2.8 bar.
7. Fuel injector cleaned
8. I checked for air leaks after the MAF sensor - maintains 0.5 bar in the inlet manifold for about 15 minutes and there was no leakage of air.

What else should check out? Morning start the engine by the 3rd time.

Last edited by oem; 09-05-09 at 11:44.
Reply With Quote
  #8 (Post Link)  
Old 09-05-09
zornzan's Avatar
Status: -
AO Member
 
Join Date: May 2008
Location: South Africa
County: KwaZulu-Natal
Posts: 91

Member car:

alfa 147 2.0 TS

Re: Engine detonations - poor or rich fuel mixture??

Replace hydraulic lifters
Reply With Quote
  #9 (Post Link)  
Old 09-05-09
oem's Avatar
oem oem is offline
Status: -
Newbie
 
Join Date: Feb 2009
Location: Bulgaria
County: Veliko Tarnovo
Posts: 17

Member car:

Alfa 156 1.8 Twin Spark

Re: Engine detonations - poor or rich fuel mixture??

Why? They can not hear tract?
Reply With Quote
  #10 (Post Link)  
Old 09-05-09
Status: Banned for not following the site rules
Unregistered
 
Join Date: Feb 2008
Location: United Kingdom
County: Wiltshire
Posts: 9,721
Images: 6

Member car:

146TS+Ti,156 Sele x2 + V6

Re: Engine detonations - poor or rich fuel mixture??

I' think you've had the belt done recently, the inlet cam asn't been tightened up and it's bent the valves allowing the ignition to backfire.

This means time for a compression test first. If that proves fruitful and all is OK, then change the knock sensor, it may be that telling the ECU lies and puting the ignition timing out.
Reply With Quote
  #11 (Post Link)  
Old 10-05-09
oem's Avatar
oem oem is offline
Status: -
Newbie
 
Join Date: Feb 2009
Location: Bulgaria
County: Veliko Tarnovo
Posts: 17

Member car:

Alfa 156 1.8 Twin Spark

Re: Engine detonations - poor or rich fuel mixture??

Sorry. I was not very good English and is not well understood the first sentence. If it comes to camshaft belt is changed and is gearing special tools.

Compression engine is good because it accelerates well. I have no cost of oil and a maximum speed reached 240 kilometers per hour on the speedometer.

I want to say that when declutch coolant temperature sensor ignition morning is good.

EDIT:
Problems with poor fuel mixture is only 30 seconds after the initial ignition. He expressed only after a long stay - 5 6 hours or more. Then everything is perfect.

The first fire was very bad. Engine fail immediately after starting it. Second ignition is good. Maintain turnover in 1200 as from time to time is unstable. Turnovers to fall in 1100 and started the engine off. Is called the sound of detonation.

I did AlfaDiag experience with the first ignition of the engine. I watched the angle of ignition. It was 3 degrees before TDC. By pressing the gas pedal angle of light changes to -3 degrees after TDC. After 30 seconds operation of the motor has stabilized and the angle of ignition in the range goes. Between 9 and 12 degrees after TDC.


All other data management engines were the norm.

1. Quantity air idling - 9 kilograms per hour
2. Air temperature - 27 degrees
3. Engine temperature - 30 degrees
4. Injection time 5 MS.
5. Lambda is cold and still not working.

Is it possible after a long stay in the car the fuel line to the tank back in the morning and having to gnaw engine light remains air. And the second is already starting to run normally?

Or is it possible to have a plunger which opens to the end?


Alfa Romeo 156

Last edited by oem; 10-05-09 at 20:04.
Reply With Quote
  #12 (Post Link)  
Old 11-10-13
Status: -
Newbie
 
Join Date: Jan 2013
Location: Lithuania
County: Klaipeda
Posts: 2

Member car:

Alfa Romeo 156

Hi, same problem for about 6 months maybe you know a solution?
Reply With Quote
Reply

Go Back   Alfa Romeo Forum > Supported Alfa Romeo Models > Technical & Vehicle Assistance > Alfa 147, 156 & GT

Tags
detonations, engine, fuel, mixture, poor, rich

Thread Tools


Recently 'Read'
No History to show

Useful Links
Lost Password?
AO Merchandise
FAQs
Register

External Links
2013 Alfa Romeo...
Alfa romeo gt...
2010 alfa romeo...
1996 alfa romeo...
2005 ALFA ROMEO GTV...

Alfa Romeo

Recent Image

Alfa 159

View paul.o's images

Search

Forums

Classifieds
   

Gallery

Social Groups
   

Members
   


Did you know..?
Did you know..?
We take privacy seriously, this is why we advise you to check your privacy settings by visiting your profile area and selecting "Profile Privacy".


New To Site? Need Help?

All times are GMT. The time now is 04:12.


Powered by vBulletin®
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Relevant URLs by vBSEO ©2011, Crawlability, Inc.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733